"The situation is fluid but as of the weekend, 140 pharmacies, mainly in the Dublin area, have informed the HSE they will withdraw from the methadone scheme from Monday, " said a HSE spokesman.

"This is a major concern as the majority of recovering addicts get their methadone from pharmacies. If they cannot get methadone, addicts may revert to opiates and this could endanger their lives, " he warned.

The HSE has set up 11 alternative sites in the Dublin area where recovering addicts will be able to get their methadone if their local pharmacy has withdrawn the service.

But health officials are understood to be appalled that the pharmacies have used recovering drug addicts to oppose the HSE's cost-cutting move.

Last month, the HSE announced that it was reducing the current medicine wholesale mark-up it pays to pharmacies from 17.6% to 8% from next January and to 7% from January 2009.

It said the move would save the HSE 100m in 2008 and was part of its ongoing efforts to cut back on the mounting drugs bill which has quadrupled from 490m 10 years ago to almost 2 billion today.

But the Irish Pharmaceutical Union said the move will put smaller pharmacies in particular out of business.

Richard Collis, who runs a pharmacy in north Dublin, said he was very reluctant to withdraw from the scheme but felt the HSE had given him no choice.

He said that he and other pharmacists were shocked to receive a letter from the Competition Authority last Friday saying their action was in breach of section 4 of the Competition Act.

"This is like Moscow, " he said.