Colombo, Jan 18 (Agencies): Sri Lanka warned on Monday that food prices could shoot up after devastating floods in the north and east of the country destroyed rice and vegetable crops.

Disaster Management Minister Mahinda Amaraweera said vegetable prices had already been affected because of the impact on growing areas that were swamped by unusually heavy monsoon rains.

More than a million people were displaced by the floods that began nine days ago and at least 40 people have died.

"We have a buffer stock of rice that is good for three months. That means there will be no immediate impact on the price of rice, but vegetables are already going up in price," said Amaraweera.

Sri Lanka's annual inflation rose to 5.9 per cent in December compared to 3.4 per cent a year earlier, with the issue set to figure in the local Government elections due by March.

Sri Lanka recently began importing chicken and eggs in a bid to stabilise local prices, but the minister said it would not be practical to import vegetables too.

He said the authorities were still working out the economic cost of the devastating floods, which some local experts have said could amount to USD 500 million.

The United Nations said it was working on the rehabilitation and rebuilding costs before launching an international appeal for funding.

The UN has also warned that left over mines from Sri Lanka's separatist war, which ended nearly two years ago, may have shifted during the floods and could pose a threat to relief workers and residents.

The Disaster Management Centre said the number of people in state-run relief centres dropped to 58,000 on Monday, down from about 240,000 on Sunday.

The Centre said water levels had rapidly fallen, but the weather office in Colombo said the monsoon conditions would last until mid February.