The Irish swimmer appeared before an international sporting panel in Switzerland on Monday to try to overturn a four-year ban.

It was imposed by swimming's governing body Fina last year after she was accused of tampering with a urine sample.

"I don't have to prove my innocence here," she told the International Court of Arbitration for Sport in Lausanne when asked whether she had added whisky to the sample.

'Alcohol odour'

Albert and Kay Guy, the husband and wife team who supervised the drugs test in January 1998, said they noticed an odour that could have been alcohol after the sample was decanted into containers.

Kay Guy said she had been unable to see De Bruin actually produce the sample, but then noticed a "sweet whisky smell".

De Bruin, who remained impassive through most of the testimony, said there was a brief period when she took her eyes off the sample after she had produced it.

And her lawyer Peter Lennon noted that the Guys stored the sample in its sealed container in their refrigerator over the weekend before shipping it to the testing centre in Barcelona.

"For us this case is a case of tampering," Fina lawyer Jean-Pierre Morand told the panel.

"Something happened with those samples and I don't think it can be disputed."

National hero

Competing under her maiden name of Smith, De Bruin rocketed to fame when she won three Olympic gold medals and a bronze at the 1996 Games in Atlanta.

She quickly became Ireland's Olympic heroine, but a whispering campaign against her soon started, alleging her victories were obtained through the use of performance enhancing drugs.

She has always denied charges of cheating, but last August she was banned by Fina from competing for four years for tampering with the sample.