Mount Mayon has erupted more than 50 times in the last four centuries [AFP]

Thousands of people living near the slopes of Mount Mayon in the central Philippines have fled their homes after the volcano spewed lava and sent ash plumes high into the air.

Soldiers and police oversaw the evacuation around the Mayon volcano on Tuesday, amid concerns that an eruption could occur at any moment.

"After the series of ash puffs and ash explosions of 1,000 metres [high], we cannot rule out a major explosion," Cedric Daep, the head of the disaster relief operations in the eastern Bicol region, said.

Daep said the authorities aimed to evacuate nearly 50,000 people from villages within eight kilometres of the volcano by Thursday.

Volcanologists raised the alert level on the 2,460-metre high volcano to two levels below eruption on Monday after lava was seen dripping from the crater.

However, the national volcanology institute also said Mayon could yet calm down and might not necessarily erupt.

Frequent eruptions

Officials said it is unlikely that villagers would be able to return home before Christmas, the biggest holiday of the year in the mainly Catholic country.

"It's 10 days before Christmas. Most likely people will be in evacuation centres, and if Mayon's activity won't ease down we will not allow them to return to their homes,'' Jukes Nunez, a provincial emergency management official, said.

Mayon is the most active of 22 volcanoes in the Philippines, having erupted more than 50 times in the last four centuries.

Residents in Albay province are used to moving away from Mayon, which spewed ash last month and prompted some villages to flee.

The last time the volcano erupted was in 2006.

Mayon's most destructive eruption came in 1841 when lava flows buried the town of Cagsawa and killed more than 1,200 people.

The country lies on the volatile "Ring of Fire", a belt of volcanoes circling the Pacific Ocean that is also prone to earthquakes.