Cape Town — Zimbabwe's President Robert Mugabe has barred the former United Nations Secretary-General, Kofi Annan, the former United States President, Jimmy Carter, and the advocate for the rights of women and children, Graça Machel, from entering Zimbabwe.

The three were due to arrive in Zimbabwe on Saturday to assess the country's growing humanitarian crisis. Millions of Zimbabweans are facing food shortages, the country's educational and health systems are grinding to a halt and there have been outbreaks of cholera.

But news agencies reported that the group had been denied travel visas. The organizers of the visit, the group of former leaders calling themselves "The Elders," said in a statement on Saturday that "the government of Zimbabwe has refused to cooperate in any way to make the visit possible."

Delegations of "Elders" from the group, including Carter and Archbishop Desmond Tutu of South Africa, have in the past visited other areas of conflict, including Darfur, with the co-operation of the governments concerned.

Annan said in Saturday's statement that he had prepared for the visit by speaking to "many regional leaders" in southern Africa, who welcomed the proposed visit.

"Millions of people are in need of help in Zimbabwe," Annan said in the statement. "We want to use our influence to increase the flow of assistance, immediately and in the longer term, to stop the terrible suffering. We are here to show solidarity with the people of Zimbabwe and to assure them that they are not alone."

Machel - also the wife of Nelson Mandela and the widow of former Mozambican president and Mugabe ally Samora Machel - said the Zimbabwean government's ban on the visit was "deeply regrettable."

"People are dying from hunger every day... and hospitals are unable to treat the sick. With schools struggling to stay open, children are missing out on an education. One in four children has lost one or both parents... We want to talk to the people and hear their stories directly"

The delegation is already in South Africa. Carter said the group would remain in the region to learn as much as it could about the situation in Zimbabwe. The Elders was formed in response to an initiative by British businessman Richard Branson and musician Peter Gabriel.