Robert Mugabe denies plans for snap election in Zimbabwe

His comments contradict his earlier threats to push for a poll before a new constitution is in place. "We do not do things unilaterally," the 87-year-old said in Harare.

"Things must be done properly within the GPA (the Global Political Agreement). There has been an outreach process and now we are moving towards drafting the new constitution."

Under the GPA - the 2008 deal that forced Mugabe to share power with the opposition - constitutional reforms are meant to ensure the next election is free and fair.

But the opposition Movement for Democratic Change (MDC), still struggling to wrest any real power from Mugabe in the two-year-old unity government, fears the President's Zanu PF party will find a way of subverting the process.

MDC leader and Prime Minister Morgan Tsvangirai said: "I know for certain that there are people in Zanu PF who know that Zanu PF cannot win a free and fair election. "So they want to return to their old methods of violence, coercion and intimidation."

There has been a surge in political violence in Zimbabwe in recent months, leading to fears of a repeat of the 2008 election when hundreds of opposition supporters were killed.

Irene Petras, of Zimbabwean Lawyers for Human Rights, said "We have a number of cases where people were attacked and then they reported it to the police, only to be arrested as the perpetrators."

In another sign that Mugabe might be preparing for an early vote, he has stepped up his campaign against western sanctions. He is also pushing for the "indigenisation" of foreign companies - requiring them to sell 51% of their shares to Zimbabweans. Mugabe's fast-failing health may also be a factor in Zanu PF's impatience for an election. He has been in power for 31 years.