Traces of artificially-produced testosterone have been discovered in the urine of triple Olympic swimming champion Michelle de Bruin, sports officials said yesterday.

The world governing body FINA announced last month that both samples of a random urine test on De Bruin showed evidence of tampering. The case has now gone to FINA's doping panel.

International Olympic Committee medical chief Prince Alexandre de Merode said a Barcelona laboratory used a new test to look for evidence of an artificially-produced banned hormone. Testosterone is also produced naturally in the body. The Irish swimmer provided the urine sample in January.

De Merode refused to give the result of the analysis but two sports officials said the laboratory had said it found signs of testosterone which had been produced artificially.

De Bruin, who has denied manipulating her sample, could not be punished if the result was confirmed, because the test has not been recognised officially as a method for catching competitors who take drugs.

The two officials confirmed independently that traces of artificial testosterone had been found in De Bruin's sample.

"That is correct. The lab did find that," one said. "But there has been no big noise made about it."