“We can no longer as athletes simply ignore what happens before the Olympic Games when human rights are systematically violated and the freedom of the press is trampled on,” said Stefan Pfannmöller, a bronze medallist in the canoe at the 2004 Athens Games.

He called on athletes to wear the plastic green and blue bracelet, which states “Sport for human rights” during the Games which start in August.

The call made on a German social website used by sportsmen and women, www.netzathleten.de, has been signed by former German handball star Stefan Kretzschmar, 1992 Olympic swimming champion Dagmar Hase, and four-time Olympic rowing champion Katrin Boron.

“I wouldn’t want anyone not to be able to achieve their dream by not participating in the Olympic Games, but what is happening in Tibet is a violation of human rights,” said Kretzschmar, who retired in June.

“This is why we have to participate in the Olympic Games while at the same time showing our commitment to the respect of human rights.”

The German Olympic Committee (DOSB) on Monday ruled out a boycott of the Games. But EU External Relations Commissioner Benita Ferrero-Waldner raised the threat of a boycott of the Beijing Olympics Games over Tibet in an interview with a German newspaper to appear Sunday.

Ferrero-Waldner also called on European companies that operate in China to demand respect for human rights and for peaceful demonstrations worldwide on the issue in the interview with Bild am Sonntag.

“There are five months left before the opening ceremony,” she said. “We should watch exactly how Beijing behaves during the coming weeks before deciding on boycott measures.”

She added: “Companies that are active in China should particularly demand respect for human rights. We cannot stop business from one day to the next. But in a situation such as the one in Tibet, companies have a responsibility.”

The commissioner said the Chinese government should negotiate with representatives of exiled Tibetan spiritual leader the Dalai Lama “with the aim of ending the discrimination of the Tibetan people.”

The protests began in Tibet’s capital, Lhasa, on March 10 and erupted into widespread riots in the city four days later. They later spread to neighbouring Chinese provinces with a heavy Tibetan presence.

China says rioters killed 18 innocent civilians and two police officers. But exiled Tibetan leaders have put the death toll from a Chinese crackdown at about 140 Tibetans and say another 1,000 people have been injured.