Bruised, bloodied and bowed, the Zimbabwean opposition leader Morgan Tsvangirai withdrew from Friday’s presidential run-off election and called on the world to “intervene and stop the genocide” in Zimbabwe.

His decision, announced hours after thousands of ruling party militiamen stormed the venue where Mr Tsvangirai had planned to hold his main rally, grants unopposed victory to Robert Mugabe, who has sworn to rule Zimbabwe until he dies.

The European Union decried the development as “a travesty of democracy”, while David Miliband, the Foreign Secretary, said that Zimbabwe now faced “a crisis of legitimacy”. The United Nations Security Council will raise the crisis today.

The Zimbabwe Electoral Commission chairman George Chiwesh said last night that the election would take place. “The commission is going ahead with plans for the June 27 presidential run-off election which are now at an advanced stage,” he said. “As far as the commission is concerned the run-off is going ahead as Tsvangirai has not formally communicated his withdrawal.”

In response, the opposition Move ment for Democratic Change (MDC) said that it would formally withdraw Mr Tsvangirai from the vote today. “The unfortunate thing is that they [Zimbabwe Electoral Commission] want to jump the gun. We will give them their letter,” Nelson Chamisa, the MDC spokesman, said.

At a press conference at his home in Harare, Mr Tsvangirai said that he could no longer call on his supporters to risk their lives by voting for him. “Mr Mugabe has declared war and we will not be part of that war,” he said. “We will no longer participate in this violent sham of an election.”

His withdrawal followed a campaign of terror orchestrated by Mr Mugabe’s military-backed regime that was unleashed after Mr Tsvangirai won the first round of voting in March.

More than 80 people have been killed, hundreds more wounded and tens of thousands displaced in a systematic campaign of violence by ruling Zanu (PF) militias. The brutality has increased sharply in the past two weeks with the wives and children of MDC supporters mutilated and burnt alive. Mr Tsvangirai called on the United Nations, the African Union and the Southern African Development Community (SADC) to intervene in Zimbabwe and “stop the genocide” of his supporters.

Mr Miliband said Mr Mugabe had crushed any hope that free and fair elections could be held. “We now face a critical crisis of legitimacy. The only people with any shred of democratic legitimacy are the [MDC],” he said. He pointed to a growing chorus of condemnation from Africa over what he called “state-sponsored violence”.

His strong words were matched by those from Zambia, which called SADC’s silence scandalous and demanded international action.

Thabo Mbeki, the President of South Africa, said he hoped that Mr Tsvangirai would meet Mr Mugabe to “find a solution to the challenges that face Zimbabwe”.

The UN Security Council is set to raise the Zimbabwe election today after the United States and Britain won a behind the scenes battle to get it on the agenda, despite resistance from South Africa, backed by Russia and China. A Security Council diplomat said that Mr Tsvangirai’s withdrawal “changes the dynamic” of the meeting. But deep divisions within the 15-member council will make any agreement on how to act difficult.

Mr Tsvangirai’s pullout came as a shock to many after a statement only 24 hours earlier assuring doubters that he was still in the fight. His announcement followed a meeting at which top MDC officials were divided over the course ahead. In the end, Mr Tsvangirai maintained the decision had been “unanimous”. He said that he would issue new proposals on how to proceed on Wednesday.

The MDC has suffered a series of debilitating setbacks in recent weeks. Mr Tsvangirai has been unable to campaign because of constant police harassment and Tendai Biti, his deputy, faces the death penalty on charges of treason.

The decision to withdraw from the ballot came when more than 1,000 armed Zanu (PF) militia gathered on the site in central Harare where Mr Tsvangirai was due to address a rally, and beat and dispersed his supporters.

Mr Mugabe’s ruling Zanu (PF) party was quick to gloat, claiming Mr Tsvangirai had “no other option” than to quit the run-off “to avoid a humiliating defeat”.

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