More than 12,000 residents have already fled to evacuation centers after the 2,462-metre (8,077-foot) Mayon volcano, in central Albay province, began spewing ash on Saturday and unleashed burning mud and rocks on Sunday.
“There is an ongoing forced evacuation from the municipalities of Daraga and Legazpi because of the lava flow,” Romina Marasigan, spokeswoman for the National Disaster Risk Reduction and Management Council, told reporters.
“The lava flow has reached some areas around three kilometers away from the volcano.”
Manila’s airport authorities said Cebu Pacific had canceled flights to nearby Legazpi City for a second day on Monday, citing bad weather.
Philippine Airlines said it had not canceled any flights to and from Legazpi, but there were some delays.
Mayon’s most destructive eruption was in February 1814, when lava buried a town and killed 1,200 people. It last erupted in 2014, spewing lava and forcing thousands of people to evacuate.
The Philippines raised the volcano alert to level 3, which indicates increased volcanic activity toward a hazardous eruption, late on Sunday. Level 5 indicates an eruption is in progress.