Hollywood actor Charlie Sheen today confirmed he is HIV-positive.

The Platoon actor, 50, speaking to Matt Lauer on American morning TV show Today, revealed he was diagnosed four years ago.

There was widespread speculation about Sheen's health in the media in the days before the interview.

Speaking to Lauer at NBC's studios in New York, Sheen said: "I am here to admit I am HIV-positive and I have to put a stop to the onslaught and barrage of attacks and sub-truths that are threatening the health of so many others."

In a letter to Lauer that the host read on air, Sheen said: "Sadly my truth soon became their treason as a deluge of blackmail and extortion took centre stage in this circus of deceit."

Asked how many people he had paid, Sheen said: "I don't want to guess wrong but enough to bring it into the millions, and what people forget is that is money they are taking from my children."

Lauer said Sheen had told him off-camera that he had paid out upwards of 10 million US dollars (£6.6 million) in the "shakedowns", and asked the actor about his financial situation as a result.

Sheen replied: "It's not great, it will be great again. I'm a survivor, I've been up, I've been down. I've been rich, I've been poor, I've been unemployed. It's another chapter in my life."

Revealed: Celebrities who have disclosed their HIV/AIDS diagnosis

Sheen rose to fame in films such as Ferris Bueller's Day Off and Wall Street and was once the highest paid actor on television for his sitcom Two and a Half Men.

He was fired from the show in 2011 after a series of angry and rambling interviews and public appearances in which he declared he possessed "tiger blood" and "Adonis DNA" and described his own behaviour as "winning".

He told Lauer that episode came on the back of being diagnosed.

Sheen, who is the son of West Wing actor Martin Sheen, has long struggled with substance abuse and spent time in rehab. He has also admitted to soliciting prostitutes and testified in the tax evasion trial of Hollywood madam Heidi Fleiss in 1995.

In May, Martin, 75, said in an interview he felt "powerless" during his son's public breakdown.

He told Radio Times: "What he was going through at that time, we were powerless to do much, except to pray for him and lift him up."

Sheen has been married three times and has five children.

Glasgow Times:

His first marriage was to Donna Peele, his high school sweetheart, and his second to former Bond girl Denise Richards (pictured).

Richards and Sheen have two daughters together, Sam and Lola. The couple finalised their divorce in November 2006.

Glasgow Times:

In 2008, Sheen wed for a third time, to Brooke Mueller (pictured), with whom he has twin sons - Bob and Max.

Wedding number four was on the cards when he announced his engagement to adult film star Scottine Ross, but it was called off after a few months.

Sheen also has a daughter with a high school girlfriend.

Dressed in a navy blue suit with a pale blue tie loosened at the collar, Sheen said he was diagnosed after suffering from headaches and migraines and sweating in bed.

He said: "I had to be hospitalised, I thought I had a brain tumour, I thought it was over."

He added: "It's a hard three letters to absorb."

Asked by Lauer if people have demanded money to stay silent about his diagnosis, Sheen said: "I have paid those people - not that many, but enough."

Asked how many, he said: "I don't want to guess wrong but enough to bring it into the millions, and what people forget is that is money they are taking from my children."

In a letter to Lauer that the host read on air, Sheen said he had been the victim of "unsavoury and insipid types" after he led with "condoms and honesty when it came to my condition".

In the letter he wrote: "Sadly my truth soon became their treason as a deluge of blackmail and extortion took centre stage in this circus of deceit."

He said he had been betrayed by people deep in his inner circle and when asked by Lauer if he was talking about blackmail or shakedowns, Sheen said: "We are talking about shakedowns."

Asked by Lauer why he brought such people into his house, Sheen said: "I was so depressed by the condition I was in, I was doing a lot of drugs, I was drinking way too much and making really bad decisions."

Asked if he had knowingly or unknowingly transmitted HIV to any of his sexual partners, Sheen said: "Impossible."

He admitted he had had unprotected sex since he was diagnosed, saying: "Yes, but the two people I have done that with were under the care of doctor and completely warned ahead of time."

Joined by his physician, Doctor Robert Huizenga, from UCLA, Sheen said he was feeling more relief than he thought possible.

Asked about Sheen's condition, Dr Huizenga told Lauer: "He has an undetectable level of the virus in his blood."

Asked if reports that Sheen has Aids are true, the doctor said: "Charlie does not have Aids. Charlie has none of those, he is healthy, he does not have Aids."

Addressing whether Sheen can transmit the disease, Dr Huizenga said: "Individuals who are optimally treated have an incredibly low ... it's incredibly rare to transmit the virus."

Sheen said he takes four pills a day and told Lauer he is no longer on drugs but admitted he has not stopped consuming alcohol, saying: "I'm still drinking a little bit."

Dr Huizenga also addressed whether Sheen could be trusted to keep up his medication, saying: "We're petrified about Charlie - we're so, so anxious that if he was overly depressed or abusing substances he would forget the pills."

He added: "Somehow in the midst of incredible personal mayhem he has continued to take these pills."

In the final segment of the three-part interview, Sheen said he was expecting lawsuits from sexual partners as a result of his revelation.

"I would be predicting the future and assuming the worst. I can only imagine, based on what I've already experienced and been forced to deal with, I'm sure that is next."

Asked by Lauer if he expected to face criminal charges because in 35 US states it is illegal to not disclose an HIV diagnosis to a sexual partner, Sheen said: "Having divulged it is the reason I'm in the mess I'm in, having all the shakedowns. I can't sit here and protect against all of that. I can only sit here with you and tell my truth."

Lauer said Sheen had told him off-camera that Sheen had paid out upwards of 10 million US dollars (£6.6 million) in the "shakedowns", and asked the actor about his financial situation as a result.

Sheen replied: "It's not great, it will be great again. I'm a survivor, I've been up, I've been down. I've been rich, I've been poor, I've been unemployed. It's another chapter in my life, it's not commerce driven, it's socially driven."

Sheen also confirmed he had recently told his oldest daughter, and his second wife Richards and third wife Mueller have known about his diagnosis for some time.

Glasgow Times:

Why Charlie Sheen was once one of the highest paid actors on TV:

At his career's peak, Charlie Sheen earned a reported 1.8 million dollars (£1.2m) an episode playing Charlie, the hedonist bachelor star of Two and a Half Men.

No wonder he was the highest paid actor on television: the part fitted Charlie Sheen almost perfectly.

Sheen, 50, has, with remarkable consistency, maintained a reputation as one of Hollywood's most notorious hellraisers for the best part of 20 years.

Alcoholism, drug abuse, allegations of domestic violence and a very public meltdown have defined him in the public eye as much as his insatiable philandering - Sheen has racked up five engagements, three wives, five children, countless flings, and even a few months living with two girlfriends he called "goddesses".

Glasgow Times:

Born Carlos Irwin Estevez in 1965, Sheen is the youngest son of Martin Sheen (above), the actor who played president Josiah Bartlet in the 1999-2006 television series The West Wing.

Like his father, who was originally known as Ramon Antonio Gerardo Estevez, he took a stage name: Charlie Sheen. Being expelled from school for poor grades and low attendance did not stop Sheen junior from breaking into film by the end of his teens.

Glasgow Times:

Making his debut in Red Dawn, a 1984 film about high school students who resist a Soviet occupation of the United States, Sheen played a cameo role in Ferris Bueller's Day Off (1986) as a lothario delinquent, had his first leading role (pictured above) as a Vietnam-posted soldier in Platoon (1986), and starred alongside his father in the dark finance drama Wall Street (1987).

A string of further credits followed, but Sheen the man was beginning to steal the show from Sheen the actor. Having split up with his childhood sweetheart, with whom he had one daughter, Sheen accidentally shot his new fiancee, Kelly Preston, in the arm.

She broke off the engagement, and Sheen soon married Donna Peele, a model, but they divorced in 1996 when it emerged he had been a client of a prostitution ring run by Heidi Fleiss, the Hollywood Madam whose escort agency was exposed three years earlier.

By the late nineties, Sheen's over-indulgences were threatening his health. He suffered a stroke after injecting cocaine in 1998, subsequently checked into rehab, before fleeing hours later.

It was a sign of Sheen's notoriety that he played himself in a bit-part in Being John Malkovich (1999). He married the actress Denise Richards in 2002, and had two daughters with her, but she divorced him in 2006 accusing him of alcohol and drug abuse and threats of violence.

Despite off-screen chaos, Sheen helped Two and a Half Men to award after award from 2003, his role as bad boy Charlie Harper having more than a little in common with his private life.

A three-year marriage to the actress Brooke Mueller ended in early 2011. Sheen had assaulted her in 2009 and been forced into rehab once more. Social services took Sheenand Mueller's twin sons, and Sheen's public meltdown, which had begun with his being fired by from Two and a Half Men earlier that year after a series of incoherent rants directed towards Chuck Lorre, the show's creator.

Claiming that he was a "warlock" with "tiger blood", Sheen, by now living with his two "goddesses", released a video in which he told viewers, "I'm not bi-polar, I'm bi-winning."

The "goddesses", former porn star Bree Olson and model and designer Natalie Kenly, had left Sheen by the summer of 2011. Sheen recovered from his meltdown to star in Anger Management, a sitcom that lasted until 2014 despite being panned by critics, as a baseball player-turned-therapist - also called Charlie.