GENEVA - Some 1.8 million people could be exposed to the worst winds from a super typhoon currently bearing down on the disaster-struck Philippines, the UN's humanitarian agency said Friday.

"We are extremely concerned," said Elisabeth Byrs, spokeswoman for the UN Office for the Coordination of Humanitarian Affairs.

"Eight and a half million people live in the line of the typhoon and 1.8 million people live in areas along the path of the strongest winds."

The category four Typhoon Pepeng (international codename Parma), which is heading towards the Philippines, is expected to make landfall Saturday.

It is expected to hit many of the areas already devastated by Typhoon Ondoy (Ketsana), which left 293 dead and 419,000 people crammed into 526 makeshift evacuation centers in the Philippines.

Some 736,000 people have also been displaced, Byrs said.

Authorities have said they would forcibly evacuate any residents who refused to flee the path of the new storm.

Parma was packing gusts of up to 185 kilometres per hour (115 miles per hour). The government defines a super typhoon as one with sustained winds of 175-200 kph and the potential to cause severe damage.