World sports science expert Arne Ljungqvist said his campaign to get controversial sex tests scrapped from the Olympics had advanced yesterday when the IOC agreed to consider leaving them out of a new medical code.

The IOC is currently drafting the details of a new code aimed at getting all international sports federations to use the same methods and penalties to nail drug cheats.

Leading world athletics official Ljungqvist said IOC legal experts, who are trying to make sure the rules are legally watertight before they are put to the federations to sign later this year, had agreed to consider dropping gender verification from the code.

"This is a step forward. We need to put all our concentration on the battle against drugs," the Swedish official said after an IOC meeting.

Ljungqvist, a member of the IOC's medical commission, has been trying for some time to persuade the organisation to abandon gender testing because he claims it is unreliable, unethical and illegal in some countries.

Female competitors have been required to undergo the tests since the 1968 Mexico City Olympics. Testers analyse cells scraped from the inside of the cheek to determine gender through chromosomes.

But Ljungqvist claims the test had become outdated by rapid advances in genetics. Athletics' governing body abandoned them in 1992.

Nevertheless, IOC officials confirmed tests would be carried out at the Nagano Winter Olympics, which start on Saturday.

Some IOC leaders believe that doing away with the tests would make it impossible to hold separate events for men and women in the future.

But Ljungqvist maintains the test is not useful because there are men with chromosomes like females and vice versa. About one in 400 females at the 1996 Atlanta Olympics tested male but all were cleared by subsequent physical examinations.

There are also worries that the tests are illegal in some countries such as Norway and could be challenged by an athlete in the civil courts.