The International Judo Federation (IJF) made the decision at its Council meeting in Tunis to strip 27-year-old Tong of the title she won at the World Championships in Rotterdam last year after she tested positive for clenbuterol.

But controversially the IJF have decided not to award the gold medal to Britain's Karina Bryant, who Tong beat in the final by Ippon to clinch her fourth consecutive world title having won her first at Osaka in 2003.

Tong's ban is due to end in September 2011 but she will still miss London 2012 under a new International Olympic Committee (IOC) rule that prevents anyone competing in the Games who has tested positive since the last Olympics.

Tong had produced one of the most memorable moments of the Olympics in Beijing when she came from behind to beat Japan's reigning champion Maki Tsukada with an Ippon with only 15 seconds remaining.

Details of the positive test and punishment were released by Chinese officials.

"The banned substance Tong took is clenbuterol, which is used for blood vessel dilation in medical treatment," said Zhao Jian, deputy head of China's Anti-Doping Agency.

"But a clenbuterol overdose can boost muscles, like an anabolic steroid.

"Clenbuterol is not an advanced anabolic steroid and it is very easy to test for.

"We had tested Tong last year before she went to the Netherlands but found nothing."

The most high-profile athlete to have tested positive for clenbuterol was Germany's Katrin Krabbe, the 1991 world 100 and 200 metres champion, who was banned from the 1992 Barcelona Olympics after testing positive for the drug.

Tong claimed to the Beijing Morning Post newspaper that she had never taken any drug intentionally, but accepted the ban.

"I don't need to take drugs to win any competition," said Tong.

"It [clenbuterol] might come from the contaminated pork I had everyday.

"I'm really sad.

"But I accept the result now."

Ma Wenguang, the director of China's Weightlifting, Wrestling and Judo Administration Center, warned Tong that she could face further sanctions.

The gold medal was the only one won at the World Championships in Rotterdam.

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