Manila  - Philippine authorities Wednesday stepped up relief efforts for more than 2 million people affected by devastating floods caused by tropical storm Ketsana, which killed at least 246 people.

Forty-two people were still missing in the wake of the worst flooding in Manila and surrounding provinces in over 40 years, the National Disaster Coordinating Council said.

Defence Secretary Gilbert Teodoro said the government dispatched teams to try to reach areas in Manila and surrounding provinces that were still inundated.

"We will bring some water, food and medicines to these affected areas," he said.

Teodoro said authorities would also clean up nearly 600 evacuation centres, which house more than 389,000 people, to help prevent the outbreak of diseases.

Some evacuation centres were set up in basketball courts, municipal gymnasiums or areas outside buildings that were filthy and ill-equipped to house the displaced families.

With some streets blocked with stalled vehicles and debris, Teodoro said the military would start operations to clear roads for faster relief work.

"The armed forces will conduct massive clean-up activities," he said. "The United States has also dispatched equipment to help in the clean up."

The Philippines earlier issued an appeal for international assistance and aid has began to pour in.

On Wednesday, the Manila-based Asian Development Bank (ADB) pledged 3 million dollars to provide clean water, health services, medical supplies and other essential emergency items.

"The Philippines is ADB's home and we are dedicated to helping flood-affected families through this unimaginably difficult time," ADB President Haruhiko Kuroda said.

The European Commission, Australia, the US, Japan and China earlier pledged assistance worth 4.12 million dollars.

Ketsana struck the Philippines Saturday, dumping one month's worth of rain in Manila and outlying provinces. The rainfall was the heaviest in the capital since 1967.

Damage to property and agriculture was estimated at 4.8 billion pesos (102 million dollars).

The Philippines was also bracing for a new storm that could hit early next week. Storm Parma, packing maximum winds of 75 kilometres per hour, was moving from the country's south-east coast. (dpa)