FACTBOX: What might the world do about Zimbabwe?

(Reuters) - Below are answers to some questions on what Africa and the rest of the world may do about Zimbabwe following President Robert Mugabe's re-election in a one-candidate ballot branded violent and unfair by observers.

African leaders were meeting in Egypt on Monday and Zimbabwe's crisis is expected to dominate the summit.

WHAT IS HAPPENING AT THE AFRICAN UNION SUMMIT?

Mugabe quickly flew to the African Union summit in Sharm el-Sheikh after his inauguration on Sunday, which followed swiftly on the announcement that he had won an unsurprising landslide victory as the only candidate.

Mugabe's arrival at the summit pre-empted any possibility he could have been discouraged from attending, even if some countries might have preferred him not to be there. He has joined the meeting with other heads of state.

Morgan Tsvangirai's opposition had called on African leaders not to recognize Mugabe, who went ahead with the vote in defiance of calls from Africa and abroad to postpone it after Tsvangirai withdrew over violent attacks on his followers.

WHAT OPTIONS DO AFRICAN LEADERS HAVE?

Observers from three African groups -- including the African Union's own monitors -- have already criticized the vote. But it is unclear whether the African Union would go as far as to reject the vote outright -- and in so doing deny Mugabe regional legitimacy -- or to use more diplomatic language.

African countries have already made clear that they do not favor the toughened sanctions sought by the United States, former colonial power Britain and other Western states.

One African minister said at the summit that many west and east African countries wanted to take a firm stand on Zimbabwe, but that southern African countries were divided on the subject.

The African Union has also played down any prospects for sending AU peacekeepers to Zimbabwe, an idea some had floated.

The most likely option is that African countries will push for Mugabe's ZANU-PF party and Tsvangirai's Movement for Democratic Change to enter negotiations on some sort of unity government.

Regional powerhouse South Africa has already been pushing this line. South African President Thabo Mbeki is the Southern African Development Community (SADC) mediator on Zimbabwe, but has faced criticism for quiet diplomacy that has achieved little.

WHAT DO WESTERN COUNTRIES WANT?

The United States and European Union have visa bans and financial restrictions on members of Mugabe's inner circle as well as sanctions on arms exports. They are already discussing how their sanctions could be broadened.

The United States has said it would push for action by the U.N. Security Council. One option would be to push for a global arms embargo on Zimbabwe although it is unclear whether that would be backed by countries such as South Africa, Russia and China.

Western countries have also been wary of taking any action that could deepen the suffering of ordinary Zimbabweans, caught in the economic collapse of the once relatively prosperous state.

WHAT EFFECT COULD ANY MEASURES HAVE ON ZIMBABWE?

The limited sanctions applied so far have done little but increase the determination of Zimbabwe's elite to keep power.

Mugabe defied regional, as well as international pressure, in going ahead with the vote, but now it is out of the way he has shown ready to negotiate with the opposition. Political analysts say he may believe he is now in a stronger position.

WHAT WOULD COME OUT OF NEGOTIATIONS?

Negotiations now look a likely scenario given the regional pressure and the fact that both sides have said they would be willing to accept them in some form, but it is far from clear they would end the crisis.

The question of who would lead a unity government is critical.

Mugabe's ZANU-PF would say that was his place as the elected president. Tsvangirai's Movement for Democratic Change would claim the post on the basis of his victory in the first round of voting on March 29. It is unclear whether either would accept a compromise candidate.

Mugabe might favor a government led by him in which Tsvangirai was stripped of any real power, but that could effectively destroy the opposition.

There is also a very important question of what a unity government would do and whether its job would be to hold fresh elections within a specified time frame.

The longer any negotiations drag on, the more they might favor Mugabe since he is already in power. The attention of other countries could easily drift to other issues as the elections recede into the past.

WHAT IF THE CRISIS DRAGS ON?

The prospects of reversing Zimbabwe's economic meltdown are slim without a change in government. Mugabe refuses to consider reforms and Western powers are unlikely to provide the billions of dollars in development aid needed to bail out the economy.

Zimbabwe's neighbors could be swamped with an even bigger influx of refugees than the 3 million who already left. Investors keen to invest in Zimbabwe will keep plans on hold.

(Reporting by Harare and Johannesburg bureaux; Editing by Matthew Tostevin)