LONDON (AP) -- A British runner who tested positive for steroids quit the Olympic team Sunday (Saturday night EDT) while track's ruling body agreed to postpone his arbitration hearing until after the Sydney Games.

 Mark Richardson, the 400-meter national champion found with nandralone in his system in October 1999, was cleared by UK Athletics in July. But the IAAF declined to accept the ruling and ordered Richardson to an arbitration hearing.

 The hearing was set for Sept. 16 in Sydney, the day after the opening of the Olympics. No new date was set.

 Richardson, who has maintained his innocence, said he was "gutted by the withdrawal." UK Athletics, the national governing body, said the postponement would "allow Mark further time to produce new scientific evidence to clear his name."

 "My ultimate aim has been to prove to the IAAF that I did not commit a doping offense," Richardson said. "We have already proved this at a national level, and I have every confidence that we shall do this again."