The US military will send troops and equipment to the Philippines to help victims of massive flooding that has affected more than two million people, the American ambassador here said on Wednesday.

Ambassador Kristie Kenney said a planned joint military exercise between US and Filipino forces would instead be transformed into an aid operation for survivors of the deadly weekend disaster, which claimed at least 246 lives.

"We are working with the Philippine armed forces to redirect a long-planned exercise," she told reporters in a visit to a cramped evacuation centre in the capital Manila.

"There will be medical teams, equipment to help clear debris, bulldozers, forklifts, and we will have some heavy-lift helicopters so we can help start cleaning up Manila so people can move on with their lives," she said.

Philippine armed forces spokesman Lieutenant Colonel Romeo Brawner said that five heavy trucks, five Humvees, one bulldozer, two forklifts and 30 US medical personnel had already arrived in the country to help in flood relief.

The Americans would bring other relief goods, including four million dollars worth of medical supplies, she added.

The ambassador did not specify how many US troops would arrive in the country.

"We will have medical teams of 30 to 40.... How many will be needed to operate the trucks and forklifts, I dont have that number," she said.

A small contingent of US soldiers, already based in the Philippines to train local forces combatting Muslim extremists, has been helping flood relief efforts in Manila since the weekend.

Tropical Storm Ketsana dumped the heaviest rains in more than four decades on Manila and surrounding areas on Saturday, submerging 80 percent of the nation's capital.