Robert Mugabe was accused last night of preparing a war against Zimbabwe's people, in an attempt to overturn the opposition's presidential election victory.

Morgan Tsvangirai, leader of the opposition Movement for Democratic Change, who has already claimed outright victory in last Saturday's election, even though the official count has yet to be released, said the government was reviving the war veterans and party militias to bludgeon the opposition into submission and terrorise voters before a run-off ballot.

'Violence will be the new weapon to reverse the people's will,' he said. 'Militants are being prepared. War vets are on the warpath.'

Tsvangirai called Mugabe a lame-duck President and said he 'must concede to allow us to move on with the business of rebuilding and reconstructing the country'.

He said the MDC was reluctant to take part in a second round of presidential elections because of the mounting climate of fear - although he stopped short of threatening a boycott. Tsvangirai said: 'It is unfair and unreasonable for President Mugabe to call a run-off.'

He reiterated his claim that taking such action was unnecessary as his party claims he won 50.3 per cent of the vote. Opposition officials said the party would launch a new court effort today to force the official election commission to publish results, after armed police prevented lawyers from entering court yesterday.

Mugabe appears to have emerged from one of the most turbulent weeks of his 28-year rule, which began with the shock of looming political oblivion, as determined as ever not to admit defeat.

South African President Thabo Mbeki warned the world yesterday not to rush to intervene in Zimbabwe. He insisted the lengthy delay in announcing the results was for checks to be carried out ensuring that there was 'no controversy' over the result.

Mbeki, who will hold talks with Gordon Brown today, is leading efforts to resolve the crisis. He said it 'was time to wait' and see what happened in a potential re-run of the elections.

Brown, who yesterday used a press conference at a summit of world leaders attended by both men to repeat calls for the results to be published, is expected to tell Mbeki privately that there is a limit to how long Zimbabwe can wait.

But Mbeki said the elections had been conducted in accordance with the rules and the delay was due to verification by the Zimbabwe electoral commission.

Because of Britain's history as a colonial power, the government is reluctant to be seen to meddle in internal affairs in Harare.