MANILA - The Philippines on Monday appealed for international aid as it struggled to cope with floods that killed at least 140 people and displaced nearly half a million.

"We are appealing for international humanitarian assistance... for (relief from) the effects of tropical storm Ketsana," Defence Secretary Gilberto Teodoro said in a nationally televised briefing.

"The potential for a more serious situation is there and we cannot wait for that to happen," Teodoro said, adding that he had sent a formal letter of appeal to the UN resident coordinator to the Philippines.

The appeal came after President Gloria Arroyo said Ketsana had strained the country's response capabilities "to the limit."

Teodoro said that apart from relief goods, funding and medicine, the Philippines may also ask for international rescue teams.

Social Welfare Secretary Esperanza Cabral said among the most immediate needs were heavy equipment to clear debris from the roads.

Teodoro said more wet weather was bearing down on the Philippines and could further hamper already difficult relief efforts.

"We cannot really leave it too long and if we wait and events prove to be correct in accordance to prediction, we may be too late," he said.

Ahead of the appeal, the international community had already begun mobilising aid.

US Navy commando teams fanned out across the flooded section of eastern Manila and rescued 52 marooned residents, including one woman in labour, as well as elderly residents and children.

The United States, China, Japan, Singapore and United Nations agencies also raised funds for relief work and to get the capital's health infrastructure working again.

Washington sent 50,000 dollars, China pitched in 10,000 dollars, while Singapore raised 30,000 dollars and a further 20,000 dollars to jumpstart a donations drive by the Red Cross.

Tokyo, meanwhile, said it would send 220,000 dollars' worth of relief goods to the Philippines, where rescue and emergency workers and the health infrastructure have been overwhelmed by the flooding.

The UN's World Health Organisation (WHO) meanwhile said those crammed into evacuation centres were at risk of water- and air-borne diseases. It also announced a 42,000-dollar relief fund.