Typhoon Koppu grew stronger but was moving slower towards the north-eastern Philippines as the government urged local authorities to issue forced evacuations of residents in flood-prone areas.

Local officials have been advised to conduct the “forced evacuation” of communities historically hit by flash floods and landslides, as well as coastal villages at risk from destructive storm surges that could reach as high as three metres, civil defence chief Alexander Pama said.

“The situation is critical because the winds are getting stronger and it will get stronger as (Koppu) moves closer,” he said.

Regional civil defence chief Norma Talosig said villagers have been voluntarily moving to safer ground or emergency shelters since early yesterday. She could not immediately give the number of evacuees.

Heavy rains are expected to inundate many areas on the main northern island of Luzon even before the typhoon makes landfall early today, acting weather bureau chief Esperanza Cayanan said.

Ms Cayanan said another typhoon further east and a high pressure area north of the country would hold Koppu in a “semi-stationary” position and shroud most of Luzon with an enormous band of thick rain clouds.