The World Anti-Doping Agency (WADA) is considering putting caffeine tablets back on the banned substance list after several Australian athletes, including national rugby captain George Gregan, admitted to taking them.

The tablets were removed from the list early last year but the doping watchdog is continuing to monitor their use for signs of possible abuse.

Although there is no suggestion anyone has broken the rules, WADA director-general David Howman said the agency was alarmed at the increasing use among Australian athletes.

"That's troubling, that disturbs us," Howman told reporters on Wednesday.

"The only laboratory in the world that indicates a little bit of a worrying trend, is the one in Australia.

"It was a substance that we thought wasn't being abused and wasn't being used for performance enhancing [because] you had to have at least 12 cups of coffee to get over the level or start swallowing tablets."

Howman said the issue had already been discussed by the WADA executive board and caffeine's status would be reviewed later this year.

"We will put it back to our list committee, they are at the present considering what should or should not be on the list for 2006," he said.

"They will consider not only the information from an anecdotal point of view but also from the material they've collected this year from the laboratories and we'll make a decision whether to put it back on the list."

SEVEN PERCENT

WADA's announcement followed Gregan's admission on Tuesday that he and a number of his Wallabies team mates had taken caffeine tablets before big games.

Gregan claimed the pills boosted his performance by seven percent and had been approved by the Australian Institute of Sport.

Several top Australian Rules Football players have also admitted using caffeine tablets after getting approval from their clubs.

"Most guys take it before the game and that sustains them to halftime when they'll do the usual thing of having water or a sports supplement drink and that's it," Gregan said.

"You can get seven percent extra work output from taking these tablets and that's a big increase at this end of sport."

Gregan's admission sparked an immediate uproar in Australia with former players condemning him for going public, claiming it could encourage children to use the tablets.

"It's stupid for George to say something like that," former test player David Campese told the Daily Telegraph newspaper.

"I don't think he understands the true implications of what is a basic endorsement of this kind of substance.

"I know they're not illegal but there are kids out there who look on George as a hero."

Politicians also weighed into the doping row, with Australian Treasurer Peter Costello saying it sent the wrong message to children.

"Gee it sends a bad example ... when you down pills like that," Costello told Australian Broadcasting Corp. radio.