Opposition Movement for Democratic Change (MDC) leader Morgan Tsvangirai is due to face off against Mugabe in the second round after failing to secure an absolute majority in a disputed March 29 poll. A date for the run-off has not been set.

The MDC accuses the ruling ZANU-PF party of waging a campaign of violence and intimidation against its supporters as part of efforts to rig the vote. The government denies the charges and accuses the MDC of instigating attacks.

"At the moment we can't say the playing ground is safe or will be fair, but we are there to create a conducive environment for everybody to be confident," SADC Executive Secretary Tomaz Salomao told Reuters in an interview.

SADC monitors observed the first round of the vote in March and Salomao said the grouping planned to send a beefed up team to the run-off.

Tsvangirai had initially said he would only participate in the run-off if international observers had unfettered access, but said on Tuesday he would be satisfied if just SADC monitors attended.

"There is a decision by the AU (Africa Union) and SADC (Southern African Development Community) to increase the number of election observers to the run-off. ... The minimum is 250 in all, and the minimum for SADC only is 200 which can well go beyond 300," Salomao said.

SADC had sent 120 observers to the first round.

"The delegation is consisting of members of parliament, civil society and the private sector," he said.

But Salomao ruled out sending peacekeepers ahead of the poll as requested by Tsvangirai.

"We don't have a war in Zimbabwe and what we need to do is to address the issue and create a conducive environment and not put up a standby peacekeeping force," he said.

"We have a team on the ground to address issues and if we see there is a problem, we will solve it."

Salomao called on ZANU-PF and the MDC to help ensure the vote can proceed smoothly.

"Don't provoke each other, stay in your corner, mobilise your fellows, present your programmes. ....That's how they should behave."