PHIVOLCS issued the alert indicating an "increased tendency towards hazardous eruption" after three steam-driven eruptions and dozens of rockfalls on Sunday afternoon.

A "bright crater glow" at the summit crater indicates "the growth of a new lava dome and beginnings of lava flow towards the southern slopes," the agency said.

The agency recommended creating an 11 km (7 mile) danger zone around the volcano to mitigate against "rockfalls, landslides and sudden explosions or dome collapse."

The tweet also advised pilots not to fly near the summit since ash could be hazardous to aircraft.

The last time Mayon erupted, the volcano exhibited similar activity beforehand, PHIVOLCS Director Renato Solidum told CNN Philippines.

Over the weekend, authorities ordered the evacuation of areas at the foot of the volcano. More than 900 families from 16 neighborhoods in the vicinity of the volcano were moved to shelters in neighboring towns, CNN Philippines quoted the National Disaster Risk Reduction and Coordinating Council (NDRRMC) as reporting.

However, Solidum added that the activity so far may not lead to an explosive eruption.

"Sometimes this eruption activity need not really result (in) very explosive eruptions. Sometimes it would result (in) non-explosive eruptions where lava would ooze out of the crater, but not explode," Solidum said.

Active volcano

Situated on the island of Luzon, about 330 kilometers (205 miles) southeast of Manila, Mayon is one of the world's most active volcanoes.

Since 1616, the imposing stratovolcano has erupted 47 times, with many of the explosions causing deadly mudflows and ash falls.

The volcano's most devastating eruption took place in 1814 when at least 1,200 people were killed.