MANILA, Philippines—President Gloria Macapagal-Arroyo has declared a state of calamity in Metro Manila and at least 23 provinces severely battered by tropical storm Ondoy, Defense Secretary and National Disaster Coordinating Council (NDCC) chairman Gilbert Teodoro said.

Presiding over a briefing of the NDCC aired live over ANC network, Teodoro said the President has authorized him to make the announcement of the areas under state of calamity to allow their respective local governments to mobilize resources needed in relief and evacuation operations and other assistance.

The Philippine Atmospheric Geophysical Astronomical Services Administration (Pagasa) had said that Saturday's flooding was the worst in 20 years.

Teodoro also said that focus of rescue operations are in Cainta, Marikina and Pasig, which are inundated by floodwaters since Saturday morning.

He said rescue and relief efforts by air would be done by the Philippine Air Force when possible.

Interviewed separately on radio, Teodoro also said that the United States has offered assistance but that the NDCC would still evaluate the help needed from the Americans.

The areas under the state of calamity are Aurora, Quirino, Nueva Vizacaya, Nueva Ecija, Pangasinan, Pampanga, Tarlac, Zambales, Bulacan, Rizal, Quezon, Isabela, Mt. Province, Benguet, Ifugao, La Union, Ilocos Sur, Cavite, Mindoro Oriental, Mindoro Occidental, Batangas, Marinduque, Camarines Norte, and Metro Manila.