Zimbabwe's Prime Minister Morgan Tsvangirai yesterday threatened to boycott presidential and parliamentary elections if rival President Robert Mugabe called them for 2011.

Mugabe and his Zanu-PF party, forced into a unity government with Tsvangirai's Movement for Democratic Change (MDC) after a disputed election in 2008 that was marred by violence, is pushing for early elections this year.

Tsvangirai told visiting German business executives he expected a vote by September on a new constitution, one of the prerequisites for an election.