Zimbabwean police have seized cars belonging to Prime Minister Morgan Tsvangirai's official escort and arrested his drivers for possessing beacon lights usually found on police vehicles, their lawyer said on Tuesday.

Tsvangirai also said his coalition partner President Robert Mugabe had incited violence in the capital Harare this month, in what could only heighten tension between Tsvangirai's Movement for Democratic Change (MDC) and Mugabe's ZANU-PF party.

Both had traded accusations over the violence that has left more than a dozen people wounded.

The commander in chief of the security forces is issuing indirect orders to incite violence. I am not convinced that President Mugabe and ZANU-PF are sincere about stopping violence, Tsvangirai told a public meeting.

His two drivers' lawyer, Kossam Ncube, said the men were returning from South Africa where they had taken two vehicles for maintenance at the weekend when they were arrested in the border town of Beitbridge.

Ncube told Reuters the drivers, employed by the government, had appeared in court on Monday and been denied bail after prosecutors said they were a threat to national security.

A magistrate, however, released them on bail on Tuesday.

The charges are that they had no authority to drive the vehicles with beacons, Ncube said.

If convicted the drivers could face a fine or up to two years in prison.

A police spokesman said he was not aware of the arrest.

MDC members have warned Mugabe to drop his ZANU-PF party's plans for an early election, saying the poll planned for this year could lead to a bloodbath.

Mugabe, 87 later this month, and Tsvangirai were forced into a coalition two years ago after a disputed poll in 2008, which led to mass violence, a flood of refugees into South Africa and a deeper economic crisis in the resource-rich state.

The United States last week condemned the violence and blamed Mugabe's party for the attacks.