Zimbabwean police have fired tear gas at hundreds of opposition protesters on the streets of the capital, Harare, after a court banned a protest march.
Opposition supporters marched through Harare after the court ruling
The judge ruled an opposition stadium rally could go ahead but agreed with police warnings that a march would present a threat to public security.
Opposition leader Morgan Tsvangirai was detained for five hours then released ahead of the planned demonstrations.
He later accused the authorities of treating him like a "common criminal".
Mr Tsvangirai, who was arrested at his home in Harare early on Wednesday morning, addressed supporters at the rally site, Glamis Stadium, in the west of the capital.
He told a crowd: "If this is the reaction of this dictatorship, then the elections are a farce."
The Movement for Democratic Change (MDC) is demanding a new constitution before presidential and parliamentary polls that President Robert Mugabe said would be held in March.
After the court ruling, several hundred opposition protesters had begun walking to the stadium from the MDC headquarters in central Harare.
But police told the demonstrators, who were chanting and waving placards, they were breaking the court order, before firing tear gas and charging.
A spokesman for the MDC said people trying to reach the stadium had been intimidated by heavy police presence.
On Tuesday, state radio said police suspected "sinister motives" behind the march.
The opposition warned this month it would boycott the polls if it was not satisfied with preparations to ensure they would be free and fair.
The BBC's Peter Greste, in neighbouring South Africa, says the rally was also organised to protest about the state of the economy, with unemployment more than 80% and inflation widely thought to be more than 50,000%.
The demonstration was the first test of the new public order and security act which should, in theory, allow political rallies after simply informing the police, our correspondent says.