The virtually crime-free Shetland islands - where muggings and robberies are unheard of - are being ravaged by heroin being brought in by drug gangs from Glasgow.

Police chiefs have admitted that the islands, widely considered to be some of the safest places to live in the entire UK, have a "specific issue" with the class A drug.

The drugs problem has become so bad that crime-fighting volunteer residents who run a team of sniffer dogs have got together with police to carry out a series of busts on dealers attempting to bring heroin onto the islands.

Unusually, whereas heroin-use in mainland Scotland is associated with social deprivation, the buoyant economy on Shetland has seen heroin become a drug of choice among well-off young people.

Detective Chief Inspector Michael Sutherland, Police Scotland's top drugs officer in the north of Scotland, said: "Shetland has a specific issue about heroin.

"It's like anywhere else in the Highlands and islands, if people see there is a market for it, they will target that area."

Local residents have come together to help the police tackle the rising drug problem on the islands.

Ian Davidge, 59, set up the Shetland-based charity Dogs Against Drugs in 2001 after a family friend died of a drug overdose.

The charity has a team of sniffer dogs which help police to stop drug dealers as they arrive on the islands.

He said: "We started the charity after a family friend of ours died of a drug overdose about 15 years ago.

"Our aim was to combat the drug problem in Shetland and hopefully we will eventually see an end to it.

"The drugs problem has been going on for a long time in Shetland though and I'm not surprised the police have brought this up again.

"We support the police and work hand in hand with them to stop the drug flow as it arrives on the islands.

"We check the ferries coming in from Aberdeen and we have the dogs working at the airport as well to make sure the drugs are found before they can be sold on the islands.

"It's hard to be everywhere though and it is still a very big problem, but we try to do our very best."

Ian said the problem lies in the fact that residents are doing relatively well financially.

He added: "There's a lot of money on the islands and people do relatively well. Unfortunately that means the drug users are often able to afford it.

"The community is no different from any other and unfortunately there are people who want to use drugs.

"There is no other crime to speak of, really. Shetland is a very safe place to live. It's part of the reason I love the place so much."

Ian said that the charity want to deter the gangs from bringing drugs to Shetland, and that a visible presence at the port and airport is the best way to do that.

He said: "We want the dogs to be a visible deterrent. If the gangs are coming here and see the dogs waiting at the port, then they might think twice in future.

"We also work with schools to teach the kids about the dangers of drugs. They love the dogs as well so we believe that can help prevent problems down the line."

Police believe the drug gangs are bringing in the supply from mainland cities such as Aberdeen, Glasgow and Liverpool.

But DCI Sutherland says police have been successful at stopping many dealers getting in.

He added: "What I would say about Shetland, because of the defined routes in, we're very, very successful at dealing with it.

"You probably see stuff in the media regularly about people from different parts of the country going up there, taking drugs up there, but generally speaking a huge amount of them get caught, and generally speaking, they get significant jail sentences and they get put off the island.

"We've got good processes up there, policing up there along with support from specialist units."

There have been several seizures of heroin and subsequent arrests in Shetland in the last year.

In March 2015, Dogs Against Drugs helped police seize £10,000 worth of heroin at Lerwick ferry terminal.

And the charity's sniffer dogs were involved in the seizure of £15,000 worth of heroin at the ferry terminal on February 9 this year.