?Photo shows Chinese Olympic judo champion Tong Wen. [Xinhua Photo]

Chinese Olympic judo champion Tong Wen did not take the banned drug on purpose, said her coach Wu Weifeng on Monday.

Tong was on Friday handed a two-year ban by the International Judo Federation after she tested positive for banned substance clenbuterol in last year's world championships in the Netherlands.

Tong's world title was taken away but her Beijing Olympics crown in 78kg was untouched.

Wu told Xinhua that Tong may eat some food that contained the banned substance.

"I can be sure 100 percent that she is innocent because a player at her level doesn't need to take this kind of drug," said Wu.

"She has been crowned so many times, including at the Olympics and the world championships and received no less than 100 doping tests without positive results," she added.

Clebruterol has the function of blood vessel dilatation in medical treatment and it also can boost muscle growth. Wu admitted that both of them were shocked by the news.

"Tong was astonished and in a very bad mood. She doesn't know what she did made this go wrong," said Wu.

For the 27-year-old Tong, more blow may be in store for her as the increasingly severe punishment in China could stop her from defending her title in the 2012 London Olympics.

"The investigation is going on, so we are still in discussion on what kind of punishment should be given to her," Ma Wenguang, the director of China's weightlifting, wrestling and judo administration center, told reporters on Monday.

"It is possible that we hand her another ban," he said.

The center could give Tong as much as a four-year ban according to an announcement made by the State General Administration of Sports in January, 2009 in a bid to curb doping offence in the National Games in October last year.

"As of the announcement was made, any athlete tested positive will be banned for four years," the Administration said in the announcement.

Despite of the bleak prospect, Wu said they would hold on until the last moment.

"We will not give up hopes for the London Games until the very end," she said.