The NCA says Mugabe has too many powers

The authorities had banned the protests, organised by an umbrella organisation called the National Constitutional Assembly (NCA) in protest against President Robert Mugabe's electoral victory last month.

At least 22 people, including protest leader Lovemore Madhuku, were arrested, the Associated Press news agency reported.

Police blockades also prevented protesters gathering in the country's second largest city, Bulawayo and in the rural towns of Mutare and Gweru said Douglas Mwonzora, spokesman for the NCA.

Defiant

Earlier in the day several hundred Zimbabweans had defied a police ban and taken to the streets, some waving banners demanding democratic reform.

"Police sealed off our starting point. We are trying to regroup," said Mr Mwonzora.

Tsvangirai will only discuss Mugabe's departure

Home Affairs Minister John Nkomo had warned that anti-government marches were illegal and those who took part would be prosecuted.

On Friday, President Mugabe ruled out another election, warning that he would not accept any challenges to his authority.

"The national poll will be held six years hence and let this sink in to Britain and... MDC (Movement for Democratic Change)," he said in a speech to his ruling Zanu-PF party.

Arrests

A coalition of churches, trade unions and students groups had called for massive street protests following Mr Mugabe's controversial re-election last month.

On Thursday, ahead of the planned demonstrations, 354 opposition activists were arrested and held for 24 hours, the opposition said.

The arrests came as mediators from South Africa and Nigeria had tried to reconcile Mr Mugabe's government with the opposition Movement for Democratic Change.

The MDC insists that the election was rigged and its leader, Morgan Tsvangirai has said he is only prepared to discuss the date of a new poll, held under international supervision, not any proposals for a government of national unity.