Former staunch supporters of Robert Mugabe have joined a chorus of world and church leaders calling on him to step down, as the country sinks deeper into the grips of a humanitarian crisis.

Both the Americans and the British have said Mugabe needs to step down for any power-sharing government deal to succeed, and now one of Mugabe's former supporters in the Mbeki government in South Africa has urged SADC states to halt supplies of commodities to Zimbabwe, to force political change.

Mosiuoa Lekota is the former ANC chairman and defence minister. He is now the leader of the new Congress of the People (COPE), a party formed by dissident members of the ruling ANC.

His statement will come as a surprise to many observers, especially from a man who is close to Mbeki, the SADC mediator in the Zimbabwe crisis.

Political analyst Isaac Dziya said Mugabe has lost all sense of reality but because of his arrogance and intransigence he will still refuse to step down.

'Mugabe has in effect become the very worst enemy of Zimbabwe and not the British or the United States. He's arrogant and intransigent and lives chronically in denial. He's never even made an effort to visit cholera victims,' Dziya said.

British Minister for Africa, Mark Malloch Brown, explained that while the power-sharing deal wasn't dead, Mugabe had become an absolute impossible obstacle to achieving it. Referring to a call this week by United States Assistant Secretary of State Jendayi Frazer for Mugabe to step down to clear a path for the deal to go ahead, Malloch Brown added: 'The Americans are absolutely right -- he is going to have to step aside.'

Malloch Brown offered a grim picture of the never-ending crisis by saying he doubted Mugabe would go willingly, and that offering him immunity from prosecution could be difficult.

The deadlock between Mugabe and Tsvangirai has held up any chance of ending the spiraling crisis in the country, where the spreading cholera epidemic has killed more than 1000 people and food, cash and fuel are in short supply. Analysts describe the situation in the country as being in the 'final death throes.'

A United Nations human rights expert added her voice to the growing calls for Mugabe to go by describing him as 'a mad dictator' who has 'lost all sense of reality'.

Jean Ziegler, an adviser to the U.N.'s Human Rights Council, told a Swiss radio station that the only way Mugabe can be removed from power is for Europe to convince his 'great protector South Africa' to withdraw all support for him.

In Australia, Foreign Minister Stephen Smith, has said the state of affairs in Zimbabwe has gone from catastrophic to perilous, but stopped short of endorsing a call by the former premier Malcolm Fraser to cut off the country's electricity in an attempt to force Mugabe to step down.

Fraser had said the situation was so desperate, the country's neighbours must use all means, short of declaring war, to force change - and this was just a day after ANC President Jacob Zuma said he could no longer call Mugabe a comrade.

The churches have also been increasingly vocal in their criticism and this week the Catholic Church in the region called on South President Kgalema Motlanthe to cut off electricity and fuel supplies to Zimbabwe

In a statement issued by Cardinal Wilfrid Napier, the Southern African Catholic Bishops' Conference said Motlanthe should force Mugabe to leave office because talks aimed at forming a Zimbabwean unity government have failed.

Napier also said the government should immediately freeze any assets held by Mugabe and "his cronies" in South Africa.

This call by the church came just a week after an Anglican bishop called Mugabe a 21st century Adolf Hitler and demanded that he be removed from power.

With the power-sharing process on hold, imminent change is unlikely unless the regional power house South Africa decides to toughen its stance on Mugabe. Analysts have said that cutting off electricity and blocking fuel supplies to Zimbabwe would mean that Mugabe would be gone in a week.