LINDA Scott was a serious junkie with 25 years of drug addiction behind her - - then somebody gave her the most intense hallucinogenic trip she had ever experienced. By the time the Californian had emerged from the ordeal four days later she felt cleansed, liberated and that she had finally thrown off a dependency that had hounded her for decades. "I had a window of opportunity and I went through it," she explains. "I was fortunate enough to be on the receiving end of the gift of freedom - ibogaine."

A natural alkaloid compound extracted from the roots of a West African shrub, ibogaine has been a central plank of the Cameroon-based Bwiti religion for centuries, its potent hallucinogenic properties highly prized as an effective catalyst that allows tribesmen not only to achieve spiritual enlightenment but to enjoy a euphoric haze that bestows the ability to dance all night. Now Western researchers, who claim that the drug could cut the number of heroin addicts by a third inside three years, are bringing it to Scotland.

"There are no easy words to describe ibogaine, no convenient ways to explain," says Dan Leiberman, a South African ethno-botanist who brings the results of his 12-year study of the substance to Edinburgh next month. "Taking the substance is a powerful, intense and fundamental experience that has brought a massive response from many people seeking to deal with addiction to heroin. It takes strength and determination, but finally many psychologists are beginning to recognise the healing power it commands."

Since first learning of the drug's existence from a Peruvian shaman in 1989, Leiberman has devoted most of his life to researching the effect it has had on followers of the Bwiti religion. He claims they are a people living out a completely peaceful, contented existence deep in the central African jungle and holds regular sessions on his South African farm where he introduces a collection of curious hippies and desperate heroin addicts to the drug. Although he says that many addicts have enjoyed remarkable recoveries, the sessions are never advertised and no claims are made that he offers a cure for addiction. "I facilitate the experience and monitor the events that follow," he says. "After that it is between them and the iboga."

Certainly, a growing army of ibogaine proponents is emerging to champion the drug as a major step forward in the fight to help recovering addicts. Howard Lotsof, the American researcher who has championed the drug as a detoxifying agent for over 30 years, says that experiences like those of Linda Scott, where addicts awake to find themselves completely untroubled by withdrawal symptoms, are the usual consequences of the treatment. "After a trip of 36 hours or more the subjects usually fall asleep, then wake up alert and ravenously hungry," he says. "It's a miracle for a heroin addict of ten years, who has been shooting up a gram and a half a day, to wake up wanting steak and eggs for breakfast."

Lotsof discovered ibogaine's allegedly miraculous properties in 1962, completely by accident, when as a New York film school student he was offered ibogaine. The 19-year-old hedonist - who was already using heroin regularly and had already experimented widely with hallucinogens such as mescaline, LSD and DMT - leapt at the chance. While the 33 hours that followed had only ever meant to be fun, Lotsof emerged from the party to discover that he no longer felt the need to take smack, and became immediately convinced that a radical new rapid detox method had just been uncovered.

As ibogaine is classified as an illegal stimulant in the US - so little is known about it in the UK that it does not feature on any official drugs register - Lotsof was forced to pursue unofficial research through tests on addicts over the next 22 years. In 1990 he began supervising trials on over 40 addicts in the Netherlands, with claimed results so successful that the American Federal Drug Administration expressed interest in a programme of ibogaine tests. Examples and apocryphal tales of addicts claiming to be cured by ibogaine continue to proliferate across the globe, and it would appear that some highly respected scientists share Lotsof's belief that they are on the verge of a major breakthrough in addiction therapy. Professor Piotr Popik, of the US National Institute of Health, has called the treatment "a potentially life-saving new strategy for treating addiction to a diverse range of drugs".

Opponents of giving addicts methadone as a heroin substitute - the predominant detox method in the Edinburgh area - have demanded ibogaine's use be investigated and widely promoted. While ibogaine would certainly seem to have great potential, the loud claims of its many proponents that the substance is a cure-all drug capable of combating any heavy addiction would seem extremely suspect. Linda Scott, whose personal testimony is frequently brandished as evidence of the cure's potency, experienced a rapid return of her craving for drugs, an event that led to her suicide in December 1997, less than a month after she had believed herself cured forever. The only Briton known to have completed a course of treatment, Yorkshireman Richard Harper, similarly fell off the wagon after initially believing himself free of heroin's hooks.

"It was certainly the best way of quitting I had ever come across," he said. "I was able to quit methadone without any cravings whatsoever. I don't know what has changed, but I do know that my past is not such a burden now. Ibogaine has given me a new freedom. It isn't a drug, it's something divine - which sounds stupid, but it's true."

Dan Leiberman points out that if an addict returns to his old haunts soon after the treatment he is sure to be tempted into his bad old ways. To illustrate, he describes a Johannesburg radio DJ who threw off a long-standing dependency to heroin but restarted his habit after a few months back in the social whirl. To cure himself this time, he is returning to spend many months working the ibogaine programme. "The drug will definitely get you through the withdrawal period painlessly," says Leiberman. "The problem comes later when you are still in the same environment that got you into drugs in the first place. That is the real problem, that is what Scotland must consider."

All is far from rosy, and there is still considerable concern from some researchers that ibogaine might have contributed to the deaths of addicts undergoing treatment. In 1994, Nicola, a 25-year-old German heroin addict, decided to undergo the treatment alongside her boyfriend Marcel, also a heavy drug user. At a discreet location in Amsterdam, the pair both took the substance and passed through the traditional sequence of events, an experience beginning with mild, LSD-like distortions of sound and light and ending after a three-day inner journey from which users regularly report having been transported down tunnels of light and "chanted clean" by groups of African people. As expected, Marcel awoke a new man, demanding a hearty breakfast to prepare him for the fresh, drug-free path that lay before him.

Just before dawn that day, however, Nicola suddenly gurgled, stopped breathing and died. The post-mortem that followed failed to pinpoint the exact reason for her death. It could well have been the ibogaine, but she had only taken 10 per cent of the known fatal dose. It could just have easily been the heroin that still coursed around a body still ravaged by the effects of prolonged opiate abuse. It could have been practically anything, but the real answer will never be known, argues Lotsof, until the FDA, or some other responsible body, completes the exhaustive programme of testing he believes ibogaine deserves.

To Lotsof, there are two reasons why ibogaine, despite 30 years of research, has failed to make a significant impact on the traditional medical establishment working in the field of drug addiction. First is an obvious reluctance on the part of men of science to embrace a practice only known due to its role in what is perceived to be a primitive, ignorant religion. Second, and perhaps most crucial, has been their dyed-in-the-wool conservatism. "Any new technology will be met by some resistance from the old guard," he says. "But even some of the methadone fans are finally starting to come around. The truly responsible researchers working out there want - and deserve - every possible tool at their disposal to help people dependent on drugs."

Dr Juan Sanchez-Ramos, the head of the University of Miami ibogaine research programme, is convinced that if ibogaine can throw off its common perception in the scientific community as an illegal drug similar in both use and effect to LSD, then such a tool will soon be available and a major breakthrough in narcotic treatment will have finally stepped out of the shadows.

"We have to take this out of the realm of mythology, he says. "A drug that is taboo can be extremely useful, but if it remains taboo then we will never find out."