Four opposition supporters in Zimbabwe have been arrested after demonstrating in support of the Harare mayor, Elias Mudzuri.

The opposition Movement for Democratic Change (MDC) said it hoped to have 2,000 people at the demonstration, but the police banned the protest, and arrested those who turned up.

Food shortages are common in Harare

Earlier this week the government announced it was introducing a new post of governor to run Zimbabwe's two main cities - Harare and Bulawayo - both of which are at present controlled by MDC mayors.

The opposition has condemned the government for the arrests, and what it says are police assaults on passers by.

Under tough new security laws, the police must approve all planned demonstrations.

Police spokesman Wayne Bvudzijena said the MDC activists had been arrested for carrying placards, reports the French news agency, AFP.

'Laughable'

The arrests were a "violation of residents' constitutional right to express themselves," said the MDC's Local Government spokesman Gabriel Chaibva.

Mugabe has tightened control on urban areas

Zimbabwe's eight largely rural provinces already have governors, who also sit in parliament and have wide powers.

Local Government Minister Ignatius Chombo denied that the new governors would make the opposition mayors redundant and said they would coordinate development.

But MDC spokesman Paul Themba Nyati told the BBC's Focus on Africa programme that it was "laughable" for the government, which had presided over a 22-year decline in services, to say it would now turn things around.

The new governors would usurp the powers of the elected mayors, he said.