Zimbabwe's opposition Movement for Democratic Change (MDC) leader Morgan Tsvangirai Saturday said that he will take part in a run-off presidential election against President Robert Mugabe.

'The run-off should take place within three weeks of the announcement of the results on May 2,' he said.

Tsvangirai said his party had taken the 'very difficult' decision after consulting widely with Zimbabweans.

'MDC believes our people will feel betrayed if we shied away from the final knock-out,' Tsvangirai told reporters in the South African capital Pretoria.

'We are ready for the final round,' he said, announcing he would return to Zimbabwe, which he fled several weeks ago amid fears for his safety, within two days after the election.

But Zimbabwe election commission has rejected the pressure for a speedy run-off.

According to the Zimbabwean constitution the run-off will be called for when no candidate takes more than 50 percent vote.

Tsvangirai secured 47.9 percent of the vote in official results to 43.2 percent for 84-year-old Mugabe, who is seeking a sixth term in power.

The MDC, which defeated Mugabe's party Zanu-PF in March parliamentary elections, has accused Mugabe of trying to boost his chances of re-election by deploying youth militia against opposition supporters.

Tsvangirai's party claims 30 of its members have been killed and hundreds injured in these attacks in mostly rural areas.

He also demanded 'unfettered access' to the elections for all international observers, including Southern African Development Community (SADC), the African Union and the United Nations, as well as free media access.

Mugabe's government had barred observers and journalists from 'unfriendly' Western countries from witnessing the first round of voting.

On Friday, SADC's mediator in Zimbabwe, South African President Thabo Mbeki, held talks with Mugabe in Harare, but he did not reveal the outcome.