MANILA - Government officials ordered the forced evacuation of people from two more municipalities near a restive volcano on Monday as the chief volcanologist warned of a possible hazardous eruption "within weeks or even within days".

More than 12,000 residents have already fled to evacuation centers after the 2,462-meter (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."

• LOOK: Lava flows from Mayon Volcano

Mayon, a tourist attraction because of its near-perfect cone shape, showed a bright crater glow on Sunday, signifying lava had started to flow from the crater.

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 1841, 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.

People have been advised to stay away from a 6-km (4-mile) radius Permanent Danger Zone and a 7-km Expanded Danger Zone on the volcano's southern flank.