By Bob Wylie BBC Scotland's investigations reporter

One of Glasgow's 6,000 addicts takes a dose of methadone

GPs who prescribe methadone say proposed changes will mean huge numbers dropping out of treatment and turning to crime to fund their habit.

But health officials say the claims are exaggerated and insist the service will never be jeopardised.

There are about 6,000 Glasgow addicts who get a daily dose of methadone.

About 5,000 of them are in the methadone programme run by doctors based in local surgeries.

But many GPs in the programme say Greater Glasgow NHS Board now wants to cut the costs by reducing GP involvement and creating a more centralised service.

It could be a disaster with thousands of patients leaving treatment and going back to illegal drug misuse and crime Dr Richard Watson

They say that the current GP model has one of the best records in the world for keeping people in treatment.

One of them, Dr Richard Watson, said he fears the worst.

He warned: "The proposals are deeply worrying and, potentially at least, it could be a disaster with thousands of patients leaving treatment and going back to illegal drug misuse and crime."

Research has suggested that if 500 people dropped out of the scheme the resulting crime wave would reach about �15m a year.

But health officials have accused the GPs of scaremongering.

They say they have had their money for looking after methadone patients doubled.

I can absolutely assure the public and the people receiving methadone treatments that services will continue Terry Findlay

Terry Findlay, the NHS board's director of community services, said the dispute was about money and was connected to the new GP contracts.

"The scheme is not in crisis and we will ensure that it does not get to that state," he said.

"We want GPs to be involved, if they wish to be, in the future of the methadone programme.

"We will ensure that that happens, either through the GPs or through alternative models.

"I can absolutely assure the public and the people receiving methadone treatments that services will continue."

He said the programme needed to develop and grow due to increasing demand.