Zimbabwe's President Robert Mugabe has commenced his party's campaign for the 31 July general elections, predicting a 90% victory for Zanu-PF.

But the 89-year-old leader warned it was a "do-or-die struggle" and to prepare for a "battle for survival".

The election will mark the end of a coalition government, which has stabilised the country's economy.

He is standing for president against his long-time rival Morgan Tsvangirai, who has been serving as prime minister.

The 61-year-old leader of the Movement for Democratic Change (MDC) pulled out of the second round of the 2008 presidential election, accusing the security forces and pro-Mugabe militias of attacking his supporters around the country.

He had won the most votes in the first round but, according to official results, not enough to win outright.

After Mr Mugabe went ahead with the run-off, winning with 85% of votes cast, regional mediators intervened to organise the power-sharing agreement. On Thursday, the Constitutional Court rejected an appeal by both parties to delay elections set for 31 July for a couple of weeks.

Critics says key security, media and electoral reforms demanded by regional mediators, the Southern African Development Community (Sadc), have yet to be implemented.

The MDC also warned last month that the voters' roll was in a "shambles" and the vote could be rigged.