Maputo, Mozambique, — The director of Mozambique's National Disasters Management Institute (INGC), Silvano Langa, Friday admitted that the situation in the flooded Zambezi Valley had become very worrying.

"The worst is possibly still to come," Langa warned at a press conference, "hence we must be prepared."

The main cause for concern was said to be the Cahora Bassa dam where the operating company has been trying to limit discharges so as to lessen the impact of flooding on the Lower Zambezi.

Langa said that with the continuing rains, water from upstream tributaries of the Zambezia was entering the lake at a rate of 10,800 cubic metres a second, making it extremely difficult to curtail its own outflow.

Rains in the Zambezi basin slackened somewhat this week, but further downpours were predicted for the coming days.

Authorities said, however, that should Cahora Bassa be forced to open its floodgates to the maximum, it would take about a week before the ensuing flood surge reaches the plains of Marromeu on the lower Zambezi - ample time to evacuate threatened areas.

Langa said he was optimistic that there would be a prompt response from donors to the government's appeal for assistance launched on Wednesday. In the first of such responses, the US embassy in Maputo Thursday announced a grant of 25,000 US dollars to assist victims of floods.

Explaining that the money came from the embassy's fund for disaster relief, Ambassador Sharon Wilkinson said it was just an initial response to Wednesday's appeal.

The money, an embassy statement said, was intended mainly for "logistical support, including the transportation of foodstuffs and other relief items, rescue operations and overflight of the flooded areas."