Sri Lanka spin bowler Muttiah Muralitharan could be banned for up to 12 months if he continues to bowl his doosra because his action exceeds official guidelines, the International Cricket Council said on Tuesday.

Muralitharan underwent tests on his action at the University of Western Australia after being reported match referee Chris Broad during Sri Lanka's Test series against Australia last month.

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Sources privy to his assessment said biomechanics experts believe Muralitharan should be allowed to bowl his doosra, a delivery that turns in the opposite direction to his normal off break, even though his arm straightens by about 10 degrees.

Sri Lanka Board president Mohan de Silva said after the University report arrived that he was "confident that Murali will be able to continue bowling the doosra".

However, the ICC stressed on Tuesday that "the existing regulations governing the degree to which a spin bowler can straighten his arm or 'level of tolerance' (five degrees) remain in place and will be enforced.

"...should any bowler be reported for a second time within 12 months of the first report, the ICC will convene a hearing of its own Bowling Review Group which has the power to impose a ban of up to 12 months should it determine the bowler's action is illegal."

Muralitharan, who has taken 513 Test wickets, is on the verge of overtaking West Indies' Courtney Walsh (519) to become the game's leading wicket-taker. He is expected to achieve the record in the series against Zimbabwe this month, edging back ahead of Australia's Shane Warne (517) on the way.

The 31-year-old bowled in front of 12 cameras at the University with his body strapped in reflective markers so a computer could track his action.

BAN POSSIBLE

The ICC confirmed that at this stage of the process "any decision or action arising from the report will be the responsibility of Sri Lanka Cricket.

"This includes any decision on whether or not the bowler should continue to bowl the particular delivery that has been the subject of the investigation."

But an ICC spokesman said that if Muralitharan's doosra exceeds the 'levels for tolerance' guidelines, which sources said it does, he faces a ban if he continues to bowl it.

The ICC regulations state that pace bowlers are allowed 10 degrees of flex, medium pacers 7-1/2 degrees and spinners five.

The University has suggested that further research needs to be undertaken to ascertain whether the levels are practical.

"In most bowlers it (the straightening) is more than five degrees and we don't know on what basis the ICC arrived at this," Mohan de Silva told reporters last week.

ICC chief executive Malcolm Speed, responding to media coverage of the alleged contents of the University report, clarified the background to the levels of tolerance saying:

"(They) reflect the reality that most bowlers straighten their arm to some degree when bowling.

"These current levels of tolerance are based on expert advice that suggests beyond a certain level, bowlers will gain an unfair advantage...

"As recently as last September at its meeting of Board Chief Executives in India, the ICC reviewed these levels and all countries were in agreement that the current standards should remain in place.

"There has been some media speculation that because the ICC will be conducting further research into the actions of spinners, the current levels of tolerance should not be applied in this (Muralitharan's) case. This suggestion lacks common sense."