GABORONE, July 4, 2008 (AFP) - Zimbabwe's one-man election that handed Robert Mugabe victory was marred by 'atrocities', 'mayhem' and violence against opposition supporters, a Botswanan observer team said Friday.

Ruth Seretse, chief of Botswana's 50-member team, part of a larger regional mission, said those believed linked to the Movement for Democratic Change opposition faced 'severe beatings, harassment, torture, killings and general threats of violence.

'The atrocities have been corroborated and constitute the necessary evidence to conclude that the credibility and integrity of the election process was compromised,' it said.

'The team therefore concludes that the presidential run-off election was not free and fair and does not represent the will of the people of Zimbabwe.'

Seretse, referring to Mugabe's party, said 'ZANU-PF youth and militia mounted illegal roadblocks, forcing people to attend ZANU-PF rallies and had bases where they tortured perceived opponents under the guise of re-educating them.'

She said some voters were forced to record serial numbers on their ballot papers and later submit the information to ruling party supporters in last Friday's election, boycotted by opposition leader Morgan Tsvangirai.

'This was intended to induce some voters into believing that the information pertaining to how they voted would be accessible and used against them,' said Seretse.

The team's report also spoke of severe restrictions on the opposition, including an inability to hold rallies and lack of access to state media.

MDC gatherings were routinely disrupted by ruling party militia, the report said, including the opposition's main rally ahead of the election which resulted in Mugabe winning a sixth term as president.

The team saw ZANU-PF youths armed with sticks and whips prevent the June 22 rally and beat people who had been in the area.

'Riot police passively witnessed these attacks making no attempts whatsoever to intervene,' said Seretse. 'After completing their task, these youth retreated to the ZANU-PF headquarters where they were treated to food.'

Tsvangirai announced he was pulling out of the election on the same day as the planned rally.

Observers were also targeted, having been chased from rallies and threatened, according to the Botswanan team.

'The (Botswanan) team was in particular singled out for harassment on account of perceptions that Botswana was anti-ZANU-PF,' the report said.

Botswana has taken a hard line against Mugabe, and this week called for Zimbabwe to be suspended from African Union and Southern African Development Community (SADC) meetings.

On Friday, Botswana said it would not recognise the result of the run-off election.

Its team was part of more than 400 monitors from the SADC, a 14-nation regional bloc.