At least one person died and more than 16,000 villagers were evacuated from their homes after Typhoon Koppu slammed into the northern Philippines.

Troops and police were deployed to rescue residents trapped in flooded villages in the hard-hit provinces of Aurora, where the typhoon blew ashore, and Nueva Ecija, a nearby rice-growing province where floodwaters swamped farmlands at harvest time.

After hitting Aurora's Casiguran town, the typhoon weakened and slowed, hemmed in by the Sierra Madre mountain range and a high pressure area in the country's north and another typhoon far out in the Pacific in the east, government forecaster Gladys Saludes said.

Howling winds knocked down trees and electricity pylons, leaving nine entire provinces without power while floods and small landslides made 25 roads and bridges impassable. Authorities suspended dozens of flights and sea voyages due to the stormy weather, and many cities cancelled classes due today.

By yesterday afternoon, the typhoon had veered toward the north from its westward course and was tracked over mountainous Nueva Vizcaya province with sustained winds of 93 miles per hour and gusts of up to 115mph, according to the government's weather agency.

Satellite images showed that the typhoon appeared to be losing its eye, a sign of its dissipating strength, acting weather bureau chief Esperanza Cayanan said, adding that Koppu was forecast to move at a slow pace before leaving the main northern island of Luzon on Wednesday.

While weather had begun to improve in some towns, and villagers had started to clear roads of fallen trees and debris, Koppu was still packing a ferocity that could set off landslides and flash floods, officials said.

"There's still danger," Mr Cayanan said. "We shouldn't be complacent."