Southern African leaders have suspended Madagascar from a regional bloc, with no indication on Tuesday their demands for ousted president Marc Ravalomanana to be re-instated would be met.

In an unprecedented move the Southern African Development Community (Sadc) suspended the vast island nation from the 15-nation group late Monday night, until constitutional order is restored.

"The extraordinary summit suspends Madagascar from all community institutions and organs until the return of the country to constitutional order," Sadc executive secretary Tomaz Salomao told journalists after a summit in Swaziland.

The summit also "urged the former mayor of Antananarivo, Mr Andry Rajoelina, to vacate the office of the president as a matter of urgency paving the way for unconditional reinstatement of President Ravalomanana."

The bloc's backing for Ravalomanana came as the supplanted president made a personal appeal to Sadc leaders. Diplomats said he presented his case to the summit as to why he should be re-instated. However, the ousted president made no public statement and left without speaking to reporters.

Madagascar was otherwise not represented at the meeting, as no member of Rajoelina's newly-installed administration put in an appearance.

Saki Mpanyane, a political analyst at the African Security Analysis Programme said Sadc's unusually harsh move was unlikely to convince Rajoelina to step aside.

"This is an unprecedented move by Sadc to suspend one of its member states. It is symbolic move yet very harsh," said

"I don't expect Rajoelina to immediately relinquish power, because he is right now riding the populist wave and enjoying the support of the army," said Mpanyane.

Ravalomanana was forced to resign as president of the troubled Indian Ocean island by Rajoelina on 17 March, and Sadc warned it would consider further action if its demands are not met.

"In the event of non-compliance with the above decisions, Sadc shall in collaboration with the African Union and the United Nations consider other options to restore constitutional normalcy," said Salomao.

Sadc also called on the international community to shun Rajoelina and apply pressure on him to return the country to constitutional order as soon as possible.

"I think the swift action sets a precedent for the bloc not to be seen as endorsing governments that came into power through military support," said Mpanyane.

Ravalomanana's supporters are demanding the return of their leader who resigned after the sustained opposition campaign won the backing of the army.

The African Union has also suspended the crisis-stricken nation from the 53-member body.

Political analyst Laurence Caromba said the suspension won't have serious economic ramifications for the island as it not a major trading partner within the region.

"He is going to be forced to call an election, that is the only way to legitimise his power...that would be a compromise," said Caromba.

The crisis in Madagascar overshadowed talks on rescuing Zimbabwe's economy, and leaders put off for two weeks any firm commitments to begin meeting a request for 8.5 billion dollars in aid.

Zimbabwe has sought about two billion dollars in aid and loans as a down payment on its economic recovery scheme, but so far has had little luck in swaying multilateral lenders like the International Monetary Fund or major western donors.

Finance Minister Tendai Biti said he remained optimistic that international aid would start flowing once the IMF releases a report following a mission to Harare earlier this month.

"I am absolutely positive that they will write a report that says look, Zimbabwe is bankable, there is a new brand that is being created here," Biti told reporters.

Sadc, which includes some of the world's poorest countries, has not yet made any specific offers other than agreeing to press the IMF and the World Bank to extend loans while urging western countries to end sanctions on President Robert Mugabe and his inner circle.