Tutu: 'South Africa has failed Zimbabwe'

The veteran human rights campaigner and Nobel Peace Prize winner said he was "deeply disappointed" that his own country had lost the moral high ground and that it had blocked firmer action from the United Nations.

He said: "I want to say first of all that I have been very deeply disappointed, saddened by the position that South Africa has taken at the United Nations Security Council in being an obstacle to the security council dealing with that matter.

"And I have to say that I am deeply, deeply distressed that we should be found not on the side of the ones who are suffering. I certainly am ashamed of what they've done in the United Nations.

"For the world to say no, we are waiting for South Africa's membership of the security council to lapse and then we can take action."

Meanwhile, Foreign Secretary David Miliband has branded Mr Mugabe as a "stain" on the country and said he "has to go".

Mr Miliband said: "Any sane person realises that Mugabe's misrule is only spurring Zimbabwe's descent into chaos.

"If Zimbabwe is to haul itself - with the help it needs and deserves - out of its current meltdown, Mugabe has to go.

"As long as Mugabe rules Zimbabwe he remains a stain on that country. I acknowledge he is also a stain on the international community, which has not been able to deliver the will of the Zimbabwean people."

The country is currently suffering from a cholera epidemic which has infected more than 18,000 people.

And power-sharing negotiations with the opposition party Movement for Democratic Change - widely thought to have won elections earlier this year - have ground to a halt.

Mr Miliband said he advocated a sanctions resolution from the UN, blocked last July by Russia and China. He also urged neighbouring country South Africa to do more.

"It is our strong view that this international crisis requires international attention," he said.

"It is obvious to everyone that neighbouring states, especially South Africa, have most to lose from instability in Zimbabwe and most to gain from change. That is why we continue to emphasise their role and responsibilities and to urge them to take action."