Heavy rains in the Zambezi valley have flooded four countries

The authorities have closed schools, converting them into shelters for thousands of displaced people.

President Levy Mwanawasa, in a television address, said a concerted effort was needed by the whole country to deal with the crisis.

More than 40 people have been killed in the region, and roads, crops and livestock destroyed.

Neighbouring Mozambique, Zimbabwe and Malawi have also been affected by heavy rains for several weeks, causing swollen rivers to burst their banks.

On Thursday, President Mwanawasa visited some of the worst affected areas.

"This is a national disaster and it requires concerted efforts of all of us to solve," Zambian President Levy Mwanawasa said on state television.

The government's Disaster Management Unit and the Red Cross have set up a $250m contingency fund to be used to acquire emergency shelters, such as tents, and food kits.