Edmonton methadone patients are facing "a serious and urgent situation," as a contract dispute threatens to end all of their prescriptions.

"We had been receiving phone calls of a panicked nature from people in Edmonton requesting that we take them on at the clinic in Red Deer," said Dr. Glenn Kowalsky, one of only 82 physicians in Alberta licensed to prescribe the drug.

More than 500 people in Edmonton rely on Alberta Health Services' Opiate Dependency Program to provide them with methadone, a synthetic, but addictive, narcotic used to treat heroin, morphine or oxycontin addiction.

However the clinic's three doctors are quitting at the end of June in a contract dispute.

An internal AHS memo dated June 19th obtained by CBC News requests urgent help from doctors.

"Arrangements are made for medical coverage in the clinic going forward, but the acute situation is that there is no possibility of this being adequate to cover transfer of this many patients over a short period of time," writes Dr. Michael Trew, AHS medical director for addiction and mental health.

"We're left with a gap that we're scrambling to fill," said Edmonton medical director Dr. David Mador.

"It is an anxious time for our patients and it's an anxious time for us because we're trying to organize the help that they need," he said.

The province is hoping other doctors will step up.

"If you are able to be of any assistance to some of these patients to help during the next few months of transition, it would be greatly appreciated," Trew writes. "This is a time to focus on the needs of these vulnerable individuals, rather than dwell on how we arrived at such a serious situation."

Kowalsky said he was surprised he never heard of the crisis until two weeks ago even though the province has known about it since April.

"Here it was two weeks away and a tsunami of disasterous proportions is about to break upon us and I got on line and couldn't find anything."

Kowalsky said or patients suddenly cut off from methadone will face a bleak outlook including violent illness and an inevitable return to street drugs and crime.

"Cold turkey off methadone makes cold turkey off heroin look like a walk in the park," he said. "We're going to have a whole bunch of really, really sick people."

With files from CBC's Janice Johnston