Idai disaster: Stranded victims still need rescue from heavy rains as UN scales up response.

Dire conditions persist in vast areas of southern Africa affected by Cyclone Idai as heavy rain continues to cause 'massive destruction', the UN said on Thursday, while aid teams scale up efforts to reach those most in need.

Warning that the situation is likely to deteriorate, the World Food Programme (WFP) said that people are still stranded on rooftops after the storm began its sweep through Mozambique, Malawi and Zimbabwe six days ago.

In Mozambique alone, the agency is seeking more than $121 million to help 1.7 million people affected through the next three months, WFP spokesperson Herve Verhoosel said, after the Government declared a state of national emergency.

Sofala and Manica provinces were worst-hit, and extensive damage has been caused to major roads and bridges which are now impassable.

Power networks have also been severed and are unlikely to be restored for several weeks, while thousands have lost their homes, Mr. Verhoosel told journalists in Geneva, noting that WFP drones are being used to help locate stranded populations.

Thousands isolated, entire villages 'wiped out'

According to Mozambique's National Disaster Management Institute (INGC), more than 100,000 people are still 'isolated' and without assistance in Chimoio, Dombe and other locations in Manica province.

The situation 'is likely to deteriorate even more and the numbers of people affected is expected to increase as it is raining there as we speak', Mr. Verhoosel added.

To date, WFP has provided food assistance to more than 20,000 people in Sofala, Manica, Tete and Zambezia; it aims to reach 600,000 people in the next four weeks.

But with aerial assessments over Mozambique's Buzi valley showing 'entire villages wiped out', Mr. Verhoosel stressed that needs are likely to far outstrip initial estimates.

'It is clear that the number of 600,000 will definitely go up in the coming days,' Mr. Verhoosel said. 'That has of course (an) implication on cost. If we help 600,000 people for three months, that is a cost of $42 million. If we need to help up to 1.7 million people for three months, that will be a cost of $121.5 million. Obviously, we don't have that money today.'

Zimbabwe's Chimanimani district hardest-hit

In Zimbabwe, 200,000 people urgently need food assistance in the coming three months, according to WFP.

Conditions in the hardest-hit district, Chimanimani, are severe, Mr Verhoosel explained, with 90 per cent of property significantly damaged.

Chimanimani is...