MANILA, Philippines - The Philippine Institute of Volcanology and Seismology (Phivolcs) warned on Sunday afternoon that an explosive eruption of Mayon Volcano in the Philippines is possible within days as it raised the alert level status from 3 to 4.

Phivolcs raised the alert status of the volcano in its Bulletin No. 7 issued 2:30 p.m. Sunday.

“This means that a hazardous explosive eruption is possible within days, thus, areas expected to be affected by such eruption will be accordingly extended,” said Phivolcs in its bulletin.

"We raised it to level four this afternoon because there was a sudden acceleration in the activity of the volcano," said July Sabit, head of the volcano monitoring team.

He said the number of volcanic quakes from 6:00 am Sunday (2200 GMT Saturday) increased to 463 and that the volcano was belching more sulfur dioxide (SO2) into the air.

This was a sign that "a hazardous eruption is possible within days."

However he would not give an estimate of when the eruption could take place.

In a level 4 alert, sulfur dioxide emissions may show sustained increase or an abrupt decrease, and there is also an intense crater glow, with incandescent lava fragments observed at the summit area.

Phivolcs said it is recommending an extended danger zone from the summit of 8 kilometers at the southern sector and 7 km at northern sector to ensure the safety of the public. This means nobody will be allowed within this Extended Danger Zone (EDZ).

It also said that areas just outside of EDZ should already prepare for evacuation in the event explosive eruptions intensify.

Ash, mudflow

Just hours earlier, volcanologists said an eruption could occur in two weeks.

Sabit told AFP earlier that an explosion could be expected sometime around January 1, adding that it would likely shoot a column of ash about 10 kilometers (6 miles) into the sky.

He said that although the ash was unlikely to be of direct danger to residents, there was the risk it could turn into a deadly mudflow, as happened during the last eruption in 2006, when hundreds of people were swept away.

While no one was directly killed by that eruption, tons of debris that had collected on Mayon's slopes were dislodged by a typhoon 3 months later. The avalanche of mud and boulders crushed entire villages, leaving over 1,000 dead.

Local civil defense head Raffy Alejandro said that the military and police had already evacuated more than 8,000 of the 9,000 or so families living within an 8-kilometer (5 mile) danger zone set up around Mayon.

"Those left behind are in the edges of the 8-kilometer zone. We are still convincing them to pull out," he said.

"We try to do the persuasive thing but if (it) gets bad, the governor has instructions to forcibly evacuate them," he added.

Mayon, renowned for its near-perfect cone, has erupted 48 times in recorded history. In 1814, more than 1,200 people were killed as lava buried the town of Cagsawa. With a report from Agence France Presse