Geneva  - Severe swelling of the Bismark and Solomon seas have displaced thousands in Papua New Guinea and many are in need of basic supplies like food and water, the United Nations said Friday.

The government and Papua New Guinea Red Cross estimated that over 75,000 people have been displaced and about half will need urgent help.

The floodings, which began on 8 December, hit hardest the offshore islands of Manus and New Ireland, but also affected the Western coastline of the main island.

A UN said the impact and magnitude of the sea swells were "uncommon." Its disaster assessment team arrived in Port Moresby this week.

Already, the charity Oxfam identified drinking water as the main priority, given that underground sources have been polluted and there is a risk of the spread of water born diseases.

Food rations were being handed out to those in need by the government, but aid agencies reported shortages of tents and mosquito nets.

The UN said it was still gathering information and lacked knowledge about the situation in remote areas. (dpa)