MANILA - The United Nations on Wednesday nearly doubled its appeal for funds to help the Philippines cope with the effects of back-to-back storms that left over 1,100 people dead and 1.7 million homeless.

The office of the UN's resident coordinator in Manila said the agency had revised upward its appeal to $143.7 million, almost twice the $74 million it had initially requested in October.

Of the original appeal, only $26 million have so far been raised, limiting the ability of aid agencies to effectively help those who are still in dire need of assistance, the UN said.

"Of particular concern for humanitarian agencies are the estimated 1.7 million people still displaced or living in areas that remain flooded," the UN's humanitarian affairs office said in a statement.

"These areas are likely to remain flooded for another three or four months, putting those affected at serious risk of disease outbreaks."

Tropical storm Ketsana dumped a month's worth of rain on Manila and outlying provinces on September 26, inundating more than 80 percent of the capital and washing away entire lakeshore and riverside communities.

A week later, typhoon Parma ravaged areas further north on the Philippines' main Luzon island, triggering floods and landslides.

The storms claimed more than 1,100 lives, including deaths from an outbreak of a flood-borne disease.

Of the more than nine million people affected, over 85,000 still remain in crowded evacuation centres, the National Disaster Coordinating Council said, while many others have been taken in by relatives or are staying with friends.