Leading medical experts have warned that scrapping methadone as a treatment for heroin addiction could lead to a rise in crime, HIV and drug deaths.
A group of 40 specialists from around the world have outlined their concerns in a letter to The Scotsman newspaper.
The experts expressed dismay about the "continuing misrepresentation" of the evidence on the effectiveness of the treatment.
They said methadone should be readily available to all addicts seeking help.
The group - which includes university professors and doctors who treat addicts - wrote in the letter: "No treatment in medicine works every time but methadone treatment has helped more people in the world overcome their problems with heroin than any other."
It went on: "If policy makers were to heed the critics' advice to close down methadone treatment or impose an arbitrary time limit on its administration, the community can anticipate more overdose deaths, more HIV and more crime."
The letter is a response to comments from Professor Neil McKeganey, director of the Centre for Drug Misuse Research at the University of Glasgow, who said last week more effort was needed to get people off drugs, including methadone, through abstinence.
Professor McKeganey has defended his views and claimed the signatories to the letter did not understand the extent of the drugs problem in Scotland, where 22,000 addicts are on methadone.
State of dependency
He said: "Much of the methadone programme in Scotland is not about getting people off, it's about continuing them in a state of dependency."
He claimed there were now parts of Scotland where there were more addict deaths associated with methadone than heroin.
"We don't see the evidence of stabilised addicts. You walk around the streets, you see people in the most desperate of circumstances."
But the man who organised the letter in The Scotsman, Dr Roy Robertson from the Royal College of General Practitioners in Scotland, said removing methadone would cause many more problems.
He told BBC Scotland: "A decrease in availability of methadone would give rise to all sorts of things - increasing sudden deaths, blood-borne virus spread, HIV infection, hepatitis C infection and all that social problem area that ends up with people in custody, and causes violence and criminality.
"There's a huge amount of unhappiness for people and their families and lives and communities blighted and devastated by the problems related to drug use."
The letter in The Scotsman ends by calling on policymakers to be clear about the value and importance of methadone treatment.