Johannesburg/Harare  - Zimbabweans were called to vote Friday in a presidential election branded a "sham" by the opposition and the West after opposition leader Morgan Tsvangirai withdrew from the contest.

Tsvangirai pulled out of the run-off poll citing fears for the safety of MDC supporters, leaving longtime President Robert Mugabe as the only candidate.

State-sponsored militia have killed around 90 MDC supporters since the first round of voting for president on March 29, in which Tsvangirai took more votes than Mugabe but not enough for an outright victory.

Polling stations across the country were due to open at 7 am (0600 GMT). The MDC and the US ambassador to Zimbabwe, James McGee, have accused Mugabe of deploying the military and militia to "frogmarch" voters to the polls in an attempt to produce a large turnout.

Although the vote appears certain to return Mugabe as president for another five years, it is not clear when the poll results will be made known.

Mugabe, 84, has ruled Zimbabwe since independence from Britain in 1980. (dpa)