Cocaine traces are found in toilets at the Oxford Union

It is the most prestigious debating society in the world. In its glory days, the Oxford Union attracted luminaries such as Sir Winston Churchill, Richard Nixon and the Dalai Lama. But now its fame has been tarnished by the discovery of traces of cocaine in its lavatory cubicles.

Reporters from the Oxford University newspaper Cherwell found the evidence of drug-taking in clubs and pubs frequented by undergraduates when they tested the lavatory cubicles of 17 venues frequented by students. Traces of cocaine were found at 11 of the venues.

Perhaps the most unexpected discovery was at the Oxford Union, which was founded in 1823. The Union is frequented by Oxford University students, 100 local residents and a handful of students from Oxford Brookes University.

Sapana Agrawal, the student president, said: "I'm shocked. We don't condone taking drugs. If it had been brought to our attention we would have dealt with it and contacted the police."

The Purple Turtle pub and club, owned by the Union, also tested positive. Lance Cowan, the manager, said: "We've caught a few doing drugs here and ejected them."

The drug study comes a week after the International Narcotics Control Board (INCB) reported that the level of cocaine use in Britain was now as high as in the US. The INCB estimated 2 per cent of the UK's population uses the drug.

Students contacted by the newspaper said drug dealers were attracted to Oxford because students were prepared to pay inflated prices for poor quality cocaine.

Thames Valley Police said: "You would expect to find evidence of recreational drug-taking in any city and Oxford is no exception."