FACTBOX: What's next in Zimbabwe's election?

(Reuters) - Zimbabwe said on Friday it would hold a delayed presidential election run-off on June 27 in which the opposition hopes to oust veteran leader Robert Mugabe after almost 30 years in power.

The long-awaited second round follows a disputed March 29 election in which official results showed opposition Movement for Democratic Change (MDC) leader Morgan Tsvangirai beat Mugabe, but not by enough votes to avoid a run-off.

WHAT WILL HAPPEN IN THE CAMPAIGN?

After weeks of uncertainty, Tsvangirai, who has been abroad since April 8 seeking to keep international pressure on Mugabe, has said he will take part in the run-off and will return to Zimbabwe on Saturday.

But police have banned a rally Tsvangirai was scheduled to address in Zimbabwe's second city of Bulawayo on Sunday. The opposition party has said it will challenge the ban in court.

Mugabe has said he would not allow what he says is a Western-backed opposition party to come to power.

HOW FAIR WILL THE VOTE BE?

Tsvangirai's MDC, civic groups and regional bloc SADC have said post-election violence in Zimbabwe has created conditions making it difficult for a free and fair run-off vote.

The opposition party says 40 of its members have been killed in political violence across the country, while thousands of homes have been destroyed. Mugabe and his ruling ZANU-PF party blame violence on the opposition.

ZANU-PF officials and security chiefs have been among those calling for a stop to violence, but it is unclear whether that will have much effect ahead of the vote.

Civic groups say political violence will lead to another disputed election and the opposition is worried it might not be able to campaign freely ahead of the run-off.

There are signs the opposition might not enjoy the unprecedented access to state media it had before the March 29 poll. Mugabe's government fired the head of the state broadcasting monopoly on Wednesday, amid reports that he had granted the opposition too much access on state television and radio.

WILL WESTERN POLL OBSERVERS BE ALLOWED IN?

The Zimbabwe government has maintained its position that no Western observers would be invited for the poll.

Tsvangirai has backed down on his earlier demand for participating in the run-off that more international election observers, including the U.N, be allowed to monitor the election.

Regional group SADC has said it could send more observers for the run-off than it did for the first round.