Zimbabwe's main opposition party has launched legal action against President Robert Mugabe and his Zanu-PF party's landslide victory in last week's vote.

Lawyers for outgoing Prime Minister Morgan Tsvangirai, leader of the defeated Movement for Democratic Change (MDC-T), filed an appeal with the Constitutional Court on Friday over the parliamentary and presidential election results.

The lawyers said they discovered that 870,000 names were duplicated on the voters' lists.

Douglas Mwonzora, an MDC-T spokesman, said that they would submit good evidence of vote-buying, rigging and other irregularities.

Outside the court, Lawyer Chris Mhike said that Tsvangirai wanted the elections declared null and void and for fresh elections to be held in 60 days.

The court's judges are considered loyalists of Mugabe, who has been in power since the country gained independence 33 years ago.

Voters 'turned away'

"We need to put the Zimbabwean courts before a trial," Mwonzora said just before the papers were filed.

"These are the same courts that ordered the elections to be held without reforms and we are bringing this to them, the consequences of their decision."

Electoral fraud allegations have mounted in the wake of the July 31 polls.

The Zimbabwe Electoral Commission said on Thursday that more than 750,000 urban voters were missing from the electoral list, in what they described as "a systematic effort to disenfranchise an estimated million voters".

"A total of 99.97 percent of rural voters were registered while only 67.94 percent of urban voters were registered," said Solomon Zwana, the network's chairman.

Zimbabwe's state election commission has acknowledged some mistakes in last week's disputed elections, but said that they were not enough to sway the win for Mugabe.

President Jacob Zuma of South Africa, the chief mediator on Zimbabwe, congratulated Mugabe.

'Widespread manipulation'

Britain, the United States and other Western countries have criticised the vote.

Mwonzora said according to the South African Development Community guidelines, elections must be peaceful, free and fair.

"But the SADC observers simply said they were peaceful and free, they didn't put the fair," Mwonzora said.

"So we are saying we cannot have a different standard for Zimbabweans."