Octogenarian Zimbabwean leader Robert Mugabe called on Saturday for his supporters to avoid violence in elections he says should happen this year and which he says his ZANU-PF party is poised to win resoundingly.

The veteran ruler told supporters at a rally for his 88th birthday the time had come to make up with the Movement for Democratic Change (MDC), with whom Mugabe was forced to share power after disputed and violent elections in 2008.

We used to fight each other, but time has come for us to do our politics in a much more cultured way, he said in an hour-long address at a stadium in Mutare, 270 km (180 miles) east of Harare.

Although our differences are political, we shouldn't regard them as a source of hatred. No. No violence, no violence, no violence.

Mugabe, who has held power since independence from Britain in 1980, has become a pariah in the West, blamed for running the economy into the ground and for massive human rights abuses to keep his grip on power.

One of Africa's longest-serving leaders, Mugabe is pushing for elections in 2012, a year ahead of schedule, arguing the unity government he formed with MDC leader Morgan Tsvangirai has broken down.

He repeated accusations of Tsvangirai and the MDC dragging their feet over crafting a new constitution in a bid to delay polls Mugabe says he will win.

Despite his advanced age and fears over his health, Mugabe has been endorsed as his ZANU-PF party's presidential candidate.

HEALTH CONCERNS

Tsvangirai insists Zimbabwe can only hold elections after broad reforms, including a new charter.

Critics say Mugabe's ZANU-PF has ruined one of Africa's most promising economies with seizures of white-owned commercial farms, and a more recent drive to force foreign firms to transfer majority shareholdings to Zimbabweans.

A June 2008 U.S. diplomatic cable released by WikiLeaks last year said Mugabe had prostate cancer that had spread to other organs. His doctor urged him to step down in 2008, according to the cable.

In his birthday speech, Mugabe sought to dispel concerns about his health.

I still have the strength. No going back. Forward ever, backwards never, he said, to cheers from the crowd.

Elections in Zimbabwe have often been violent, with hundreds of opposition supporters killed in the last 12 years in clashes with security forces and ZANU-PF youth militia, according to the MDC and rights groups.

(Reporting by MacDonald Dzirutwe; Editing by Sophie Hares)