GUANGZHOU - Doping has reared its ugly head at the Asian Games as a Uzbekistan judo silver medalist was caught using a banned stimulant.

Shokir Mumonov, who won a silver medal after losing to South Korean Kim Jae-Bum in the 81kg division final last Sunday, has tested positive for Methylhexaneamine, Dr. Mani Jegathesan, chairman of Olympic Council of Asia medical commission, announced here on Friday afternoon.

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"The athlete has been disqualified from the competition as well as these games and his performance in the competition has been nullified, his medal withdrawn and appropriate adjustment made to the results," said the OCA medical chief.

"His urine specimen collected on November 14 after the competition was found to contain Methylhexaneamine."

The findings have been referred to the Uzbekistan Olympic Committee, the International Judo Federation and to the World Anti-Doping Agency (WADA).

Timurnsshk Nbaev, spokesman for Uzbekistan delegation, refused to comment on the first doping case in Guangzhou.

"No comment. I am very busy right now," Nbaev said to Xinhua.

All samples collected at the Guangzhou Games are being tested at the WADA lab in Beijing, which conducted drug checks for the 2008 Summer Olympics.

"Methylhexaneamine is a new stimulant and we had just started to test this drug recently," said Beijing lab chief Xu Youxuan.

Methylhexaneamine has been the subject of several high-profile doping cases since the WADA added the substance to its banned list this year.

The substance is widely used as a nasal decongestant but is also found in recreational drugs. A component of flower oil, the substance is a common ingredient in a variety of nutritional supplements and easily available on the Internet.

Some athletes have said they unknowingly ingested Methylhexaneamine when using supplements or other products.

Nigerian sprinter Osayomi Oludamola was stripped of her Commonwealth Games 100 meters gold medal for using Methylhexaneamine. Six Indian wrestlers and three swimmers also tested positive for the drug ahead of the Games.

Last week South African rugby players Chiliboy Ralepelle and Bjorn Basson had turned in positive test samples for Methylhexaneamine following the Springboks' 23-21 win over Ireland in Dublin on November 6.

In last Asian Games in Doha, four weightlifters were disqualified for flunking doping tests.

Myanamar weightlifters Kyi Kyi Than and Oo Mya Sanda, a silver medalist in the 75kg division, both tested positive.

Uzbekistan's Elmira Ramileva was caught to have used an anabolic steroid and teammate Alexander Urinov was found to have taken cannabis.