Zimbabwean authorities on Tuesday launched an international appeal for $20 million to help some 20,000 people displaced by flooding in the south of the country following torrential rains.

Villagers living in the basin of a huge dam project that is under construction in Masvingo province have been most affected.

"The government of the republic of Zimbabwe is appealing for US$20 million from the international community to meet urgent humanitarian needs for affected communities," Local Government Minister Ignatius Chombo told Western diplomats and aid agency officials in Harare.

"This is needed to evacuate and relocate at-risk communities as well as (for) the provision of food, shelter, safe water and other basic needs," he said.

The humanitarian fund will also go towards buying blankets and tents and to build clinics and schools.

The minister said about 20,000 people who were living within the Tokwe-Mukorsi dam basin are at high risk of flooding.

No death has been recorded so far, but President Robert Mugabe declared a state of national disaster on Sunday.

The displaced have been given temporary shelter at schools and in tent camps.

Marooned villagers are being airlifted by air force helicopters. Neighbours Namibia and Zambia have pledged three helicopters to help with rescue efforts.

Tokwe-Mukorsi dam, 400 kilometres ( 250 miles) south of Harare, is being built by an Italian contractor, Salini S.p.A.

The dam is intended to feed irrigation projects for sugarcane, cotton and tobacco production.