A woman has come forward claiming the electrician, who was mistakenly shot dead by anti-terror police at Stockwell Tube last July, attacked her in London.
The claims, first made three weeks ago, were angrily denied by the de Menezes family yesterday. Patricia da Silva Armani, Mr de Menezes' cousin, said the leaking of the allegation showed the Metropolitan Police were trying to "smear" him.
She said: "The police are clearly culpable for Jean's death and now the smearing of his name. This is a disgraceful and outrageous attempt by them."
The woman, in her early 20s, contacted police in the capital last month after seeing Mr de Menezes' photograph in the media.
She told officers he bore a striking resemblance to a man who raped her in a hotel room after she became separated from her friends while celebrating New Year's Eve 2002 in west London.
She apparently also gave police a DNA sample at the time which could be compared to genetic material from Mr de Menezes' body.
Adrian da Silva Lima, Mr Menezes' former girlfriend, branded the allegations "absurd".
She said: "What she's saying is ridiculous. It's a complete lie and very painful to have to deal with."