A defiant President Robert Mugabe yesterday vowed he would 'go to war' if he lost the presidential run-off due to take place in less than two weeks.

Describing the opposition as 'traitors', he claimed Zimbabwe would never 'be lost' again. Speaking at the burial of a veteran of the independence war, Mugabe said he would never accept the Movement for Democratic Change taking over. 'It shall never happen ... as long as I am alive and those who fought for the country are alive,' he said. 'We are prepared to fight for our country and to go to war for it.'

The threat was seen as an angry response to the pressure mounting on the government from other African leaders over the regime's harassment of the MDC leadership and supporters in the run up to the 27 June election.

Yesterday, MDC leader Morgan Tsvangirai was arrested again and held for three hours as he tried to campaign in the countryside. There was also a stand-off between lawyers and police in Harare's high court before Tsvangirai's deputy, Tendai Biti, finally appeared before a judge.

Earlier, according to opposition lawyer Lewis Uriri, police had told the judge, Justice Ben Hlatshwayo, that they did not think his order to produce Biti in court was genuine. A handcuffed Biti eventually told reporters that he was 'fine'. Police said he faced treason charges - which carries the death penalty - stemming from a document they claim was a blueprint for regime change. He is also accused of spreading false information for releasing the opposition's own tally from the first vote in March.

With the MDC leadership under constant harassment, voters being beaten and killed and what amounts to a curfew in some MDC rural strongholds, the likelihood of the 27 June run-off taking place in any meaningful way seems remote.

Even if the 9,231 polling stations open, there is a shortage of officers prepared to risk monitoring them. The number of international observers the government intends to let in remains unclear. Although the first of the 400 monitors for the Southern African Development Community have arrived, they have yet to be accredited by the Zimbabwe Electoral Commission, whose own status is weakening - a memo from police chief Faustino Mazango, leaked to the Zimbabwean Independent newspaper, ordered his officers to take charge of the 'whole voting process'. Police had been, he said, 'too docile' during the March poll.

Rini Chipfunde, director of the leading independent monitoring group, the Zimbabwe Election Support Network, said the authorities were creating an environment in which only police, soldiers and ruling party officials would be present at polling stations in rural areas. 'People will be too terrified to vote,' she said. 'Others may be bussed in by the ruling party to cast their ballots under the watchful eye of police officers.'

Sources across Zimbabwe have reported an increasing number of roadblocks manned by militias and war veterans, effectively cutting people off and creating a dusk-to-dawn curfew.

James McGee, US ambassador in Harare, said 30,000 potential MDC voters had fled their constituencies. Mugabe has already ordered charities to stop work, leaving millions struggling to find food in the collapsed economy.

A total of 67 people have been killed and tactics familiar from past state violence campaigns are returning - sticks rolled with barbed wire, whippings and arson. The internationally-touted 'third way' - a Government of National Unity - has been met with stiff opposition from the military, Zanu-PF and many in the opposition who want no truck with Mugabe. Andrea Sibanda, of Matabeleland Freedom Party said: 'Whoever is floating the idea of GNU with Mugabe and Zanu-PF must be coming from another planet. How does one unite with them when their hands are dripping with blood of their kith and kin?'

In an interview with The Observer, Jabulani Sibanda, the Zimbabwe Liberation War Veterans Association chairman, also ruled out a national unity government. He said: 'We do not want the West interfering in the affairs of the country and so we are going to vote for total independence. As long as we have a government voted for by the people, there is no problem. In fact, we are still to take more farms because there are some white farmers protected by party heavyweights holding on to land that belongs to the black majority.'

Additional reporting by Mercy Mujuru in Bulawayo