MANILA - Typhoon Mitag intensified as it moved slowly towards the Philippines on Friday, triggering mass evacuations, flight cancellations and exacerbating flooding from a previous storm.

The typhoon has winds of 175 km per hour (108 miles per hour) at its centre and is forecast to strengthen.

The storm is almost stationary east of the central Bicol region, the Philippines' typhoon alley, on Friday evening, but was likely to make landfall on Saturday, weather officials said.

People in Bicol sought refuge in churches, schools and town halls as more than 50,000 people fled their homes.

Disaster officials said 200,000 people would be evacuated from Bicol, where volcanic mud from the slopes of Mount Mayon can trigger lethal landslides.

Mitag, a woman's name pronounced Me-tok from Yap in the Pacific Ocean, is expected to cut through Bicol before passing into the South China Sea by Monday.

It is currently a category 2 typhoon and is expected to intensify to a category 4 typhoon, with winds up to 250 kph, on Saturday, according to storm tracker Web site, www.tropicalstormrisk.com.

Rains from the system are likely to affect most of the central and northern Philippines, weather officials said.

Mitag comes less than a week after tropical storm Hagibis, which killed 13 people in the country and is currently in the South China Sea heading for southern Vietnam. Nearly 30,000 people were affected.

About 25 sailors were missing in the South China Sea on Friday after a Philippine fishing boat capsized in rough waters, China's Xinhua news agency reported.

The Philippine ship, numbered "805900", was carrying about 80 sailors when it sank near the Nansha Islands on Thursday morning in heavy winds.

Hundreds more fisherman from China, Vietnam and the Philippines were stranded on the Nansha Islands, a group of islets, reefs and sand banks also known as the Spratly Islands, whose sovereignty is contested.

Eight domestic flights to and from the central Philippines were cancelled ahead of Mitag and more than 800 passengers were stranded in Bicol after ships were barred from leaving port.

In Bulacan, a province north of Manila, around 40 houses were submerged after officials released water from the Angat Dam to prevent it overflowing.

Storms regularly hit the Philippines and authorities are trying to avoid a repeat of last year's devastating Typhoon Durian, which killed 1,200 people and left 120,000 homeless when it crashed through Bicol.