South African President Thabo Mbeki has said his country will "have to live with" an influx of illegal immigrants from neighbouring Zimbabwe.

Up to three million are thought to have fled to South Africa, amid a worsening economic and political crisis.

There is high unemployment, and fuel and food shortages across Zimbabwe.

Addressing parliament, Mr Mbeki said it was not possible to put "a Great Wall of China" between the two countries and stop people walking across the border.

The South African authorities regularly deport Zimbabwean illegal immigrants, but many make repeated attempts to enter South Africa, in the hope of finding refuge and employment.

The annual rate of inflation in Zimbabwe has soared to 3,731.9%, driven by higher energy and food costs, and amplified by a drop in its currency, official figures show.

President Mbeki has been appointed by Southern African leaders to mediate between Zimbabwe's governing Zanu PF party, and the opposition Movement for Democratic Change, in the hope that free and fair elections can be held next year.

Mr Mbeki said on Thursday the discussions were going "very well" but he gave no details.

It is understood however that the government and the opposition in Zimbabwe have yet to hold a face-to-face meeting.