Floods inundated towns in the northern Philippines as Tropical Storm Linfa struck the northern edge of the archipelago, where relief agencies were braced for disaster on Sunday.

The region's civil defence chief Chito Castro said that at least 11 coastal towns had been affected by floodwaters and swelling rivers as Linfa passed over the area.

"The rain is strong, the wind is strong. Major roads are impassable. Some houses are half-covered (with water), some are completely covered," he told reporters.

He said there were still no reports of casualties from the storm, but this could be because the focus was on relief efforts.

Power has also been knocked out in large areas of the north, hampering communications.

The storm, packing maximum winds of 120 kilometres (75 miles) per hour, is moving northwest at nine kilometres per hour and is expected to curve northwards, moving off Luzon by Sunday evening.

National civil defence chief Alexander Pama said "we have pre-positioned the items necessary" in case the storm prompts any massive evacuations.

The disaster-plagued Philippines is hit by about 20 typhoons and storms each year, many of them deadly.

Among the worst in recent memory was Super Typhoon Haiyan, which struck the central Philippines in November 2013, leaving more than 7,350 people dead or missing.