There has been a series of ash explosions up to 1,000m high
More than 20,000 people have evacuated homes in the Philippines after lava and ash flowed from one of the nation's most active volcanoes.
Soldiers and police directed the evacuation from around the foothills of Mayon volcano amid concerns that a big eruption could occur at any moment.
Philippine officials raised the alert level for Mayon on Monday.
Mayon, 330km (206 miles) south-east of the capital Manila, has erupted 48 times since records began.
The head of the disaster relief operations in the region, Cedric Daep, said the authorities aimed to evacuate nearly 50,000 people from villages within eight kilometres of the volcano by Thursday.
He said that after a series of ash puffs and ash explosions up to 1,000m high, a major explosion could not be ruled out.
After the most recent eruption of Mount Mayon in August 2006, huge deposits of volcanic ash were left on its slopes.
However, the volcano remains a popular tourist attraction and is famous for its perfect cone.
The Philippines is part of the so-called Pacific "Ring of Fire" that is known for its volcanic activity.
The Philippine Institute of Volcanology and Seismology lists 22 active volcanoes in the country.