* Leaders call for peace during while reviewing constitution
* New charter an important step before election
* Mugabe, in power for 32 years, presses for election in March
By Nelson Banya
HARARE, Oct 22 (Reuters) - Rivals President Robert Mugabe and Prime Minister Morgan Tsvangirai made a joint appeal on Monday for tolerance in reviewing a draft constitution whose adoption will lead to Zimbabwe's next election, expected next year.
Mugabe and Tsvangirai, who formed a coalition government four years ago after violent and disputed elections in 2008, were addressing a conference of parties and civic society groups reviewing the proposed new constitution in Harare.
Mugabe's ZANU-PF wants to overhaul some provisions limiting presidential powers while strengthening those of parliament. Tsvangirai's Movement for Democratic Change accuses ZANU-PF of retaining power through vote rigging and political violence.
The final charter is likely to be compromise as neither party commands the two-thirds majority required to railroad it through parliament. The first conference on the constitution, three years ago, was disrupted by political clashes.
"We must live up to the expectations of the people of Zimbabwe. Let us be peaceful in our conduct. Surely, settling things through fisticuffs instead of through dialogue and discussion is primitive," said 88-year-old Mugabe, who is seeking to extend his 32-year-rule.
"Our intellectual levels should lift us to that upper level where argument, dialogue, debate, discussion, deliberation should be used as a way of reaching agreement or disagreement."
Mugabe said the next poll would be in March although his opponents are still pressing for more political reforms to the avoid disputes that have marred previous elections.
Even jointly addressing delegates drawn from political parties, churches and pressure groups, the two men's positions remained poles apart on some issues.
Tsvangirai also called for calm, but contradicted Mugabe's suggestions that the two would have the final say on the draft - a position also at odds with that taken by the inter-party parliament committee driving the constitutional reforms.
Mugabe said: "There are some who are saying why are the principals (Mugabe and Tsvangirai) saying they should review the process? Because we are the ones who caused everything. Sometimes people fail to see where power is derived from."
But Tsvangirai played up parliament's role in the process.
"For the record, this process is being done in accordance with Article 6 of the GPA (global political agreement, which set up the coalition) which makes it clear that this is a parliament-driven process in which the principals and the executive must play a minimum part," Tsvangirai said.
"We have no intention whatsoever, at least on my part, to tamper or meddle with the people's views."
While Mugabe struck a conciliatory tone, describing his coalition with Tsvangirai and a smaller party as "an unholy trinity that has done some holy things", the prime minister took aim at some Mugabe allies who have been quoted as suggesting the army would not accept a Tsvangirai poll victory.
"This exercise underpins our belief in constitutionalism and the rule of law. We cannot therefore be in contradiction with ourselves by preaching a coup or a military subversion of the people's will," Tsvangirai said.
Mugabe noted the reforms had taken a long time to complete, but expressed the desire to replace the independence charter, which has been amended 19 times since 1980.
"There were so many amendments made to the (independence) constitution, it's now like a pair of trousers ... heavily patched up. We want a new one. This is the new one which we agreed to have," he said.
(Editing by Alison Williams)