Mr Mengistu left South Africa after receiving medical treatment. He faces charges of crimes against humanity in Ethiopia, where the government has been pursuing his formal extradition.

Zimbabwe is my second home. Everybody loves to be back home

Mengistu Haile Mariam

Speaking to the BBC, the former leader denied he had been forced to flee South Africa where he had been treated for a peptic ulcer.

"This thing has been exaggerated a lot," he told the BBC's Network Africa programme.

"In the first place, the present government of South Africa are my comrades in arms, my friends, my colleagues."

The government has been criticised for failing to extradite him, even though the two countries have no extradition treaty.

One of South Africa's opposition parties, the United Democratic Movement, said the government had lost an excellent opportunity to prove its commitment to human rights.

Papers late

South Africa's presidential spokesman Parks Mankahlana told The Star newspaper that Mr Mengistu had already left the country when the government received the extradition request.

"The request came on Friday evening but Mengistu had left that afternoon," said Mr Mankahlana.

"Mengistu came to South Africa as a private citizen. He came and he left."

Mr Mengistu travelled to South Africa three weeks ago on a Zimbabwean diplomatic passport with a special visa.

He has lived in exile since fleeing Ethiopia in 1991 as rebel forces closed in on the capital Addis Ababa.

Emperor Haile Selassie: Overthrown by Mengistu in 1974

The Ethiopian Government wants Mr Mengistu to face charges for the murder of thousands of opponents of his military Marxist regime during its so-called "Red Terror" campaign of 1977 and 1978.

Zimbabwe has also had extradition requests from the Ethiopian Government but has refused to act because of the absence of a treaty.

Ethiopia has argued that Mr Mengistu's crimes are such that the absence of a treaty is not a good enough reason to refuse extradition.

Ethiopian courts are already trying Mr Mengistu in his absense along with hundreds of other government officials accused of directing the killings.

He faces the death penalty if found guilty.