People in the South African country of Zimbabwe are heading to the polls for a referendum on the nation’s new constitution that would limit powers of the incumbent President Robert Mugabe.

The polls across the country have opened on Saturday at 05:00 GMT at some 9,456 polling stations and are set to close at 17:00 GMT.

The main political parties in Zimbabwe are in favor of the proposed laws that could pave the way for presidential election expected to be held in July.

The 89-year-old Mugabe has ruled the country since its independence in 1980. However, under the new constitution the winner of the July election can only serve two terms.

Meanwhile, tensions erupted between supporters of rival parties on the eve of the constitutional referendum in the capital, Harare.

Several members of Prime Minister Morgan Tsvangirai's Movement for Democratic Change (MDC) were attacked on Friday when they were putting up posters to encourage people to approve the proposed law.

The MDC accused supporters of Mugabe's ZANU-PF party of being behind the assault and MDC spokesman Douglas Mwonzora said that “The attacks are a clear testimony that ZANU-PF wants to embark on acts of violence.”

This came as ZANU-PF spokesman Rugare Gumbo has said that the Zimbabwean president wanted people to vote peacefully.

Zimbabwe's state-run Herald newspaper quoted Gumbo as saying that “He said we should not have violence and added that the party will not tolerate that nonsense whether it is intra-party or inter-party. He wants the people to vote in peace.”

Official results of the vote are due to be released within five days of the referendum.