The United Nations made an urgent appeal on Friday for millions of dollars in extra aid to help more than 300,000 people in the Philippines who were displaced by devastating floods late last year.

The UN "flash appeal" was increased to $39 million, up from $28 million requested immediately after Tropical Storm Washi washed away whole villages on th southern island of Mindanao on December 16.

The funds are urgently needed to help more than 300,000 survivors who remain crammed into makeshift evacuation sites or in tent cities, the UN said in a statement as it issued its appeal.

"Sustained, generous financial support is crucial to enable provision of basic goods and services and the rebuilding of resilient communities," said the UN's humanitarian coordinator in the Philippines, Jacqui Badcock.

The official death toll from the floods is 1,259, but many more are believed to have been buried or washed out to sea.