Zimbabwe's much-delayed drive to draw up a new constitution as part of a power-sharing deal has been suspended amid a row between the two main political parties, a party spokesman said Thursday.

The mammoth process of public consultations for a new constitution began in 2009, months after the deal between President Robert Mugabe and Prime Minister Morgan Tsvangirai, but has been repeatedly disrupted and marred by violence.

The new delay was caused by disagreements between Mugabe's ZANU-PF and Tsvangirai's Movement for Democratic Change (MDC) over the weight given to the public submissions, MDC spokesman Douglas Mwonzora told AFP.

ZANU-PF favours ranking submissions according to the number of times they were raised during meetings to gather people's views, he said. The MDC prefers an approach based on the quality of those submissions.

"ZANU-PF's proposal is populist but it leads to the emasculation of voices in wards with less people than others," Mwonzora said.

"Given that we had totally disagreed, we referred the matter to the management committee. The committee said the work should stop and they will give directions on the method to use," he said.

The constitution committee had set September for a referendum on the draft constitution but the suspension is likely to cause a delay.

Public consultations over the constitution were repeatedly postponed after outbreaks of violence, with a Tsvangirai supporter killed when militant backers of Mugabe stoned a meeting in September 2010.

Mugabe, in power since 1980, and his long-time rival Tsvangirai formed the power-sharing government more than two years ago in a bid to stop a conflict sparked by disputed 2008 elections and to mend a shattered economy.

The agreement included plans for a new constitution and amended media and election laws to ensure free and fair polls.

Although no dates have been set for fresh polls, Mugabe and his ZANU-PF party have said elections should be held this year with or without a new constitution.

Tsvangirai and his MDC party want reforms in place first to ensure a level playing field before the elections.