Kidnapped Scots journalist Alan Johnston today told of "the most unimaginable relief" as his four-month ordeal came to an end.

The BBC reporter was released from his captors in Gaza in the early hours of this morning.

A British consular official later said Mr Johnston had set off in a convoy for Jerusalem in the company of British diplomats.

Mr Johnston, 45, was the only Western reporter based in Gaza and had been working there for three years when he went missing on March 12.

After his release, he said: "It's just the most fantastic thing to be free. It was an appalling experience, being kidnapped, occasionally quite terrifying. I didn't know when it was going to end.

Timeline March 12: First reports of Alan Johnston's kidnapping in Gaza City. Palestinian security officials say he was snatched by four masked gunmen. The BBC is unable to contact Johnston and fears for his safety. March 13: Hamas-led Palestinian administration says he is being held by by a well-known group. March 19: Johnston's parents Graham and Margaret appeal for his release, saying: "It is no way to treat a friend of Palestinians." March 20: Foreign Secretary Margaret Beckett says the Government is "using every channel and opportunity" to secure Johnston's release. April 9: Colleagues hold a vigil outside the BBC's HQ in London to mark four weeks since Johnston's kidnap. April 12: BBC director-general Mark Thompson appeals for Johnston to be released and flies to Palestine to meet President Mahmoud Abbas. April 15: Palestinian group The Brigades of Tawheed and Jihad claims it has killed Johnston. April 19: President Abbas says his intelligence services have confirmed Johnston is alive. May 9: A tape from Johnston's kidnappers, The Army of Islam, is sent to al Jazeera TV. It includes demands and a picture of his BBC identity card. May 16: Johnston's 45th birthday is marked by vigils from Moscow to Hong Kong. June 1: A video of Johnston is posted on the internet. He says he has been treated well and is in good health - and criticises the British Government's foreign policy in the Middle East. June 17: The Army of Islam warns it will kill him if the situation "gets more complicated". June 20: Johnston's 100th day in captivity is marked with vigils in the UK and abroad. June 24: A video is released showing him wearing an explosives belt to deter rescue attempts. July 3: Hamas steps up pressure to free Johnston by taking up positions around the Army of Islam's stronghold. July 4: Johnston is led to freedom after 114 days in captivity.

"It became hard to imagine normal life. I dreamed several times of being free but always woke up in that room."

He later told a press conference in Gaza: "It's hard to believe I'm not going to wake up in a minute in that room again."

Mr Johnston said he had been able to listen to the radio after his first two weeks in captivity and heard messages of support.

"It gave me a psychological boost," he added.

"It was amazing to be lying in solitary confinement and hear people from Nigeria, Malaysia or friends from London, colleagues sending messages of support."

Mr Johnston said his kidnappers had initially told him they did not intend to kill or torture him but on the first night they covered his face with a hood and handcuffed him.

He said: "The leader of the gang appeared in the doorway at about two in the morning, at quite a frightening moment. He was wrapped in a red and white chequered headscarf, his face concealed behind it.

"I knew then it was a jihadi group and the group I had been scared of in Gaza."

He added: "They were often rude and unpleasant. They did threaten my life a number of times. There was one 24-hour period when they seemed to get very angry and chained me up but that only lasted 24 hours.

"They were even occasionally friendly. One of the guards would let me go through and watch his television. But it was very grim.

"It was like being buried alive and removed from the world, in the hands of people who were dangerous and unpredictable."

He said there was no violence towards him until the last half hour of his captivity.

He said his kidnappers had become anxious when Hamas took over the region's security a few weeks ago.

"They realised that they might be under real pressure from Hamas," he said. "They were worried that their hideout might be stormed."

Asked what he wanted to do now, he replied: "You know, just the simplest thing, walking through any door, going down the street, seeing friends or family, people you love, you want to do it all at one go."

He added he would spend a "few days" regaining his strength and having a rest before returning to Scotland.

Mr Johnston's parents, Graham and Margaret, said they were "overjoyed" at the end of their "living nightmare".

Speaking outside their home in Lochgoilhead, Argyll, his father said he had a very brief telephone conversation with his son.

He said: "All he said was hello dad', and I said hello son. How are you? Are you all right?' He said I am 100%' and then the phone was cut. That's all we've heard from him so far."

In a statement earlier, the family had said: "The last 114 days have been a dreadful time for us - but particularly for Alan. Through it all, we never lost hope.

"Alan had always told us of the friends he'd made in Gaza. We knew they would be there for him.

"We've always known Alan was special. But the last 14 weeks have shown us how special he is to others - to his friends in Gaza, to his colleagues at the BBC and to the listeners and viewers who've written in their thousands. Their support has buoyed us up through the darkest days. We've drawn our strength from them."

Speaking of his family, Mr Johnston said: "It's so good, the thought that I will be with them soon."

He added, in a "rare act of kindness", a guard had let him come into his room and watch a press conference at which his parents had appeared.

He said he could see that his dad was "coping with it" and that his mum was "dealing with it too".

It was a "huge relief", and after that, one of the major psychological problems was slightly eased.

But he added: "I felt so very badly for them, what I was putting them through.

"I have obviously worked in some difficult places and caused them to worry for quite a few years, but just the idea that at their age, my activities should have brought the very worst of the world's problems pouring through their normally calm and peaceful lives was something that made me feel terrible. It does now and always will."

Prime Minister Gordon Brown said: "I welcome the good news of Alan Johnston's release.

"This will come as a great relief to his family and friends and all those who have worked hard to see him freed."

A passionate perfectionist who put his life on the line

ALAN JOHNSTON knew the dangers he faced as the only Western reporter permanently based in Gaza.

Fourteen other journalists had been abducted before him since 2004.

Johnston spoke often to other BBC staff about his fears of being kidnapped and was said to have taken precautions during his three years in Gaza.

However, his worst fears turned to reality on March 12 when he was kidnapped - and became the longest-held reporter abducted in the Gaza Strip.

The journalist, who was born in Tanzania but grew up in Scotland, was preparing to return to London when he was kidnapped by gunmen as he returned to his apartment in Gaza City.

Johnston, 45, was educated at Dollar Academy in Clackmannanshire before graduating with an MA in English and politics from Dundee University and a diploma in journalism from the University of Cardiff.

He joined the BBC in 1991, working as a sub- editor in the World Service newsroom before becoming a correspondent in Tashkent, Uzbekistan, from 1993 to 1995.

He spent a year as Kabul correspondent from 1997 to 1998 but returned to London and the World Service to be programme editor of The World Today, followed by a stint as a general reporter in the BBC World Service newsroom.

His posting to Gaza, where he has worked for all BBC outlets in both radio and TV, began in April 2004 and was due to end in April 2007.

During his time in the strife-torn region, he has been an eyewitness to the inter-factional violence raging between Hamas and Fatah.

His colleagues have described him as a perfectionist with an "unsurpassed passion" for journalism who agonises over every sentence.

More than 100,000 people signed an online petition calling for his release, while vigils were held for him by journalists and campaigners across the world.

Religious and political leaders united in appealing for his safe return to the UK.