Women's Olympic shot put champion Irina Korzhanenko of Russia tested positive for an unidentified drug, Olympic medical sources said on Sunday.

Korzhanenko, 30, won the first athletics gold medal of the Athens Games on Wednesday at Ancient Olympia.

Sources close to the International Olympic Committee said the drug was stanozolol, the anabolic steroid used by Canadian Ben Johnson when he tested positive after winning the 1988 Seoul Olympic 100 metres final in world record time.

Russian Olympic team spokesman Gennady Shvets declined to confirm Korzhanenko had tested positive but said there was a "problem".

"We are looking into it at the moment," he said.

Korzhanenko, the European champion, was awarded the 1999 world indoor gold medal when Ukrainian Vita Pavlysh was banned for doping but lost the title herself after a positive test.