At least 20 people were injured when a rally by supporters of Zimbabwe's prime minister in a southern Harare suburb was attacked.

Youths threw rocks and beat up those attending the rally, called by the party of Morgan Tsvangirai, forcing organizers to shut it down.

The attackers were said to belong to the ZANU-PF party of Zimbabwe's President, Robert Mugabe.

The prime minister had been scheduled to address the rally.

A shaky unity government linking ZANU-FP with Mr. Tsvangirai's Movement for Democratic Change was formed in 2009 after disputed presidential elections. Since then, the coalition has been riven with problems and disputes.

Mr. Mugabe has led the government in Zimbabwe, formerly known as Rhodesia, since 1980.