SORSOGON, Philippines (AFP) - Hundreds of people fled their homes on the slopes of a rumbling Philippine volcano on Friday as authorities warned of rain-driven mudflows from an approaching typhoon that could bury them alive.

Around 500 residents of farming villages around Bulusan volcano, many of them children and elderly women, boarded army trucks clutching sleeping mats and bags of clothes as Typhoon Noul bore down on the area.

"I have no choice but to evacuate. I may not be strong enough to outrun the mud flows," 66-year-old housewife Dolores Guela told AFP.

Officials said she and her meningitis-stricken nine-year-old granddaughter would be among about 1,000 people taken to temporary shelters to wait out the wrath of Noul, which was forecast to bring heavy rains in the region from late Friday.

The typhoon was gusting at up to 185 kph and experts warned debris from two recent ash explosions could rumble down the slopes of the 1,559-metre volcano.

State vulcanologists subsequently raised Alert level 1 - the lowest in a five-step warning system - on Bulusan.

Minor ash explosions alone would not normally prompt an evacuation, but authorities ordered one nonetheless because of the threat of mud flows from the approaching storm.

Bulusan, on the southeastern tip of the main island of Luzon, is about 400 kilometres south of the capital, Manila. It is among the country's 23 active volcanoes.

Noul would be the fourth major storm or typhoon to hit the Philippines this year. The disaster-prone nation is lashed by an average of 20 each year, routinely killing hundreds of people.