An overwhleming majority of NRL chief executives say their clubs are not using injections of calves' blood extracts, but many have no problem with Manly treating their players with the substance while it remains legal.

But one of Australia's leading sports medicine experts believes more than one team nationwide is using Actovegin to help athletic performance.

"I believe that the product is being used very broadly around Australia by a number of sporting teams, not just one particular team in Sydney," said Dr Peter Larkins, a former Olympic athlete who has been a doctor for several prominent sports teams. "It tells me that this particular product is being sought by athletes as a way of trying to gain a benefit."

Of the 10 clubs that replied to the Herald's inquiries yesterday, not one admitted using the product and none expressed a concern that the Sea Eagles have apparently been injecting players for some time.

St George Illawarra chief executive Peter Doust said that, while his club had not used Actovegin, the Dragons' medical staff were always on the lookout for ways to improve the rehabilitation and endurance of athletes.

"We're aware of its applications, but we aren't using it because we haven't found any significant research to substantiate its efficacy, other than from the company which manufactures it," Doust said yesterday.

"The view of the professionals we have is that there's no substantive evidence to support the [endurance] view other than that conducted by that company, and we're looking for more rounded trials of such substances before we would be interested in applying it. We're always interested in ways of helping our athletes recover, from injuries in particular, because this is such a physical game."

Parramatta chief executive Denis Fitzgerald said it was up to his club's fitness staff to decide whether the product could be used. "It's not being used at our club, but I have no problem with it if it's not a banned substance," he said.

A similar view was expressed by Melbourne chief executive Brian Waldron, who agreed the injections were fair game until they were ruled out.

"To be honest, I haven't even read about it. Whatever Manly choose to do within the rules of the game is their business. If it's within the rules, I don't care."

However, Gold Coast managing director Michael Searle said the matter was a moral one and that it was up to the game's governing body to deliver a ruling.

"I suppose it's more an ethical question for the NRL rather than the individual clubs. I think it's something the game should review to see if it's crossing over the line," he said.

"It could be a bit like those intravenous drips used by the Brisbane Lions some years ago. Every club is trying to get an edge, but it's up to the ruling body to make a decision on it. I'll be guided by the NRL on it."

Canberra Raiders chief executive Don Furner couldn't say for certain whether his club had looked into using the injections.

"I haven't heard of it, but that's not to say that our coaching staff haven't. They might have tossed it around," he said.

"We're only a few hundred metres down the road from the AIS, and they should know about that kind of stuff."

Like the Dragons, the Sydney Roosters said they would rather wait for concrete evidence before looking into using the substance.

"From what I'm reading into the situation, it's legal, but whether or not it's beneficial is something only the experts can tell us," club chief executive Brian Canavan said. "I've heard about it ... but it's never been in our club."

Chief executives at Penrith, Brisbane, North Queensland and Wests Tigers all said they had never heard of the product and that it had never been used at their clubs.

Actovegin is said to have two main benefits: increasing stamina and helping recovery from injury.