Dr Joe Cummiskey, chief medical officer with the Olympic Council of Ireland, has called for further caution on the use of creatine after a report published yesterday suggested a possible link between the food supplement and cancer.

The report from the French Agency of Medical Security for Food (AFSSA) states that the use of creatine "constitutes a risk that has not been sufficiently evaluated, particularly in the long term". It also said that there is a "potential carcinogenic risk" for users of the substance.

Creatine is popular with many athletes as a training aid and is sold over the counter in most countries. It is not banned by the International Olympic Committee (IOC) although there is considerable controversy over the effects and possible side-effects of its use.

"There is a movement now to increase the regulation of creatine, especially in the US," says Dr Cummiskey, who is also a member of the IOC's medical commission. "The IOC have never banned the substance because it was never proved conclusively that it was performance enhancing. But there are a number of issues with creatine that do need to be examined.

"In my view, anyone who is using creatine is one step away from using anabolic steroids," he said. He said more regulation is needed. "I would certainly be interested to see the details of this study and I think there is the need for greater control."

The AFSSA report quoted epidemiological studies that showed creatine causing "digestive, muscular and cardiovascular problems". The report also said the use of creatine should be regarded "as contrary to the rules, spirit and significance of sport" and suggested consideration should be given to it being added to the list of banned products.

The sale of creatine is banned in France although the product is widely available in Ireland in most health food stores. It is also widely advertised in British sports magazines available here as well as being sold over the Internet.

A number of Irish sporting bodies, including the IRFU, have already made recommendations against the use of the supplement. The IRFU took a stance last year not to supply creatine to any of its national squads, although it is assumed that a number of players from schoolboy to senior level do take the supplement on their own accord.

John Murphy, the Irish schools rugby co-ordinator, admits that creatine remains popular in the sport. "You do hear of players that are taking it," he says, "but all the medical advice that we give players is against it.

"There is still plenty of material out there advertising its benefits but the medical research about possible side-effects hasn't been certain. And there is always the risk for abuse by taking extra doses."

Studies into the long-term effects of using creatine have been limited. Dr Noel McCaffrey, team doctor with the Dublin senior football team, is in the process of completing a study with UCD on the medical and psychological effects of creatine use but he also feels that long-term effects have yet to be properly evaluated.

"I have always been neutral on the issue, but I would be eager to look at this study in context, especially the doses that were involved. The bulk of the evidence so far suggests that creatine is safe for a healthy individual. And in lab settings it does appear to have some benefit. The big question is whether or not it is cheating, and in that regard a lot of people are opposed to it."

Dr McCaffrey is also aware that creatine is used in GAA circles: "In the context of good sports science it does make sense, but it could also be seen as a gateway to abuse of illegal substances. There are also obvious questions about this study, such as what type of cancer it might cause."

Also calling for more information on the French study was Jim Kilty, former national sprints coach and now a private consultant to a number of leading Irish sprinters: "Obviously one would have to take a close look, but it's certainly not the first food or vitamin supplement that has been said to have a possible link to cancer.

"Creatine is still a very popular supplement. Some of my athletes would have used it in recent years and others chose not to. And there did seem to be some positive effects in that they didn't feel as tired."

A spokesperson for a Dublin health food shop said yesterday that creatine remains popular and demand has been consistent over the past couple of years, almost exclusively in the 21-35 age-group.