The Prime Minister warned President Robert Mugabe that the world's patience was "running thin" with his failure to release the results of the poll after almost two weeks.

But in spite of reports of state-sponsored violence and a ban on political demos, South African President Thabo Mbeki insisted there was "no crisis".

And as he and other African leaders met, without Mr Mugabe, to discuss the issue, the veteran Zimbabwean leader dismissed Mr Brown as "a little tiny dot on this world".

Human Rights groups such as Amnesty International reported credible information suggesting a programme of "co-ordinated retribution against known and suspected opposition supporters".

The opposition Movement for Democratic Change (MDC), which claims it won victory at the ballot box, was on Friday banned from public demonstrations.

Mr Brown said: "The democratic rights of the Zimbabwean people have got to be respected. They have voted. The presidential election results have not been announced. We cannot wait any longer for the announcement of these results."

Talking about the meeting of the Southern African Development Community (SADC) group meeting in Zambia, which Mr Mugabe is not attending, the PM said: "I think it is important that we are vigilant about what happens after that.

"It is appalling if there is intimidation and violence. It is completely unacceptable and the whole eyes of the world are on Zimbabwe now."

The South African president met Mr Mugabe on his way to Saturday's summit, and said afterwards of the delay: "I wouldn't describe that as a crisis. It's a normal electoral process in Zimbabwe. We have to wait for ZEC (the Zimbabwe Electoral Commission) to release (the results)."