The human rights campaigner Peter Tatchell has criticised the International Olympic Committee for denying the request of the widow of one of the Israelis killed at the Munich Games for a minute's commemorative silence.

Mr Tatchell expressed his shock over the continued stubbornness of Lord Coe and Jacques Rogge, respectively the London Games chair and the IOC president, on the matter.

"I deplore the IOC's decision to not hold a minute's silence in memory of the athletes murdered in Munich in 1972," he said. "It is the most tragic event in the whole history of the Olympics. To ignore this 40th anniversary is reprehensible. "The massacre was not only an outrageous crime but also an outrageous violation of Olympic principles and values," he said. "The IOC has abdicated its moral responsibilities."

Mr Tatchell made the comments after sending an open letter to Lord Coe and Mr Rogge flagging up the Olympic Charter's prohibition on discrimination and urging them to require all competing nations to sign a pledge on this matter and ensure that no athletes were discriminated against on the grounds of sexual orientation or gender identity.

He said all nations should be made to promise "that they do not discriminate on the grounds of gender, ethnicity, religion or sexual orientation. If they refuse to sign, they should be denied participation in the games".

Ankie Spitzer's petition to the IOC, which she is planning to hand to officials in London next week, has now attracted support from 99,583 people worldwide.