Voters cast ballots in Zimbabwe amid heavy security, claims of rigging

Heavily armed riot police were deployed in Zimbabwe on Wednesday to deal with potential election flashpoints as an estimated 6.4 million eligible voters cast their votes in a country where President Robert Mugabe has held power for the last 33 years.

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Prime Minister Morgan Tsvangirai has vowed to push the 89-year-old Mugabe, who promised he would hand over power if he loses, out of office. Tsvangirai said he took Mugabe's promise "with a pinch of salt."

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Tsvangirai's party, Movement for Democratic Change (MDC), has alleged Mugabe supporters have engaged in vote-rigging in a desperate attempt to stay in power.  Despite the allegations and concern expressed by the U.S. State Department on Tuesday over "partisan behavior," the head of the African Union monitoring team, Olusegun Obasanjo, said initial reports showed a peaceful, orderly, free and fair vote was taking place on Wednesday.

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Despite that, long lines of people braved unseasonably cold weather from well before dawn on Wednesday to cast their votes.

Polls opened just after the scheduled time of 7 a.m. and some people had been lined up since 4.30 a.m. because they said it was such an important election, Al Jazeera's Haru Mutasa reported from the capital city of Harare.

Parkstone Musarurwa, 27, told Al Jazeera's Azad Essa in Harare he had lined up to cast his ballot since 6 a.m. and had not seen any intimidation.

"It's a cold morning and the environment is so cool, everyone is so happy," said Musarurwa, who added he was hoping the poll would bring change. "Nothing's going to stop me to vote."

As polls opened in one polling station in the western province of Manicaland, a key swing region, a voting line stretched more than a half mile.

State radio said thousands of officers had been sent to the central Midlands province Tuesday, while trucks of police carrying automatic rifles and grenade launchers patrolled in the restive Harare townships of Highfield and Mbare.

Those run-down districts of the capital are hotbeds of support for Tsvangirai and were at the center of several weeks of post-election violence in 2008, when 200 people linked to his political party were killed. That election cycle ended in an uneasy coalition and power-sharing deal between Mugabe and Tsvangirai forged by regional leaders.

This year's presidential and parliamentary elections have also been marked by allegations of threats and intimidation by security forces, but there have been no reports of violence.

With no reliable opinion polls, it is hard to tell whether 61-year-old Tsvangirai will succeed in his third attempt to unseat his aging rival, who has run the southern African nation since it gained independence from Britain in 1980.

Voting is scheduled to close at 7 p.m., local time, but may extend to Thursday, according to election officials. The parties of both candidates have predicted landslide victories. However, it is possible neither candidate will emerge an outright winner, triggering a Sept. 11 run-off.

Philip Victor contributed to this report. Al Jazeera and wire services