Britain's Sunday Times newspaper claimed the suicide bombers responsible for the 2005 attacks on the London transport system planned to spray the deadly gas in the teams' changing rooms during the Ashes Test at Egdbaston.
Prime Minister John Howard said Australian and British authorities were checking the report but said it was the first he had heard of any such plot. "I've checked and we certainly weren't told that," Howard told reporters.
"It may not be accurate to report we're investigating. Our people are talking to their British colleagues and if there's any further information it will be brought to light," he said.
But the report served as a reminder that "there are people around who want to do us in, who do want to do damage to Australia," Howard said.
Attorney-General Philip Ruddock said authorities would take maximum precautions to ensure the safety of players and spectators during the Ashes series that starts in Australia next month.
"We place a great deal of importance in ensuring the safety of mass gatherings and that includes not only those participating in those events but also those who watch them," he said.
Australia's cricket captain Ricky Ponting said his team was "totally confident" in security.
"We are totally confident in the security precautions Cricket Australia and the Australian Cricketers' Association (players' union) take on our behalf," he said in a statement released in India, where the team is about to play in the Champions Trophy tournament.
Cricket Australia, which is organising the Ashes, was also unaware of any sarin plot but said the risk of attacks was ever present.
"Our long-standing approach is based on a fundamental principle that safety and security of players and team management is our priority," chief executive officer James Sutherland said.
"We work with the Australian Cricketers Association to take expert security advice from as many sources as we can before we make decisions about whether tours should go ahead or not."
Australian Cricketers Association chief executive Paul Marsh said that while the threat of a sarin gas attack had yet to be substantiated, terrorism was always a worry.
"You've got to take all these types of threats seriously, and the measures that we take when Australia is touring internationally or playing even in Australia don't change," he said.