The Philippine seismological agency called Thursday for the evacuation of thousands of people from homes near a volcano south of Manila after an eruption sent steam and rock fragments hundreds of metres into the sky.
Taal volcano, which sits in a picturesque lake, has been belching sulphur dioxide for several days, creating a thick haze over the capital and several surrounding provinces, and prompting health warnings.
The last eruption in January 2020 shot ash 15 kilometres (nine miles) high and spewed red-hot lava, crushing scores of homes, killing livestock and sending over 135,000 people into shelters.
Taal burst to life again Thursday afternoon with a "short-lived dark phreatomagmatic plume" that rose a kilometre into the air, the Philippine Institute of Volcanology and Seismology said in a statement.
That was followed by "four short phreatomagmatic bursts" that produced 200-meter-high plumes above the main crater lake, it said in a later update.
The agency warned of "ongoing magmatic extrusion at the Main Crater that may further drive succeeding explosions", as it raised the alert level from two to three.
It "strongly recommends" the evacuation of the volcano island and "high-risk" areas of Agoncillo and Laurel towns.
"We're just raising the alert because something is happening and it can lead to a higher activity," Renato Solidum, head of the agency, told AFP.
Mariton Bornas, head of the agency's volcano monitoring division, said so far they "don't expect the same scenario" as last year's eruption.
A spokesman for the national disaster agency said its local agents had called an emergency meeting with government officials and emergency services. He estimated nearly 15,000 people lived in the most vulnerable areas.
Agoncillo disaster officer Junfrance De Villa told AFP preparations were underway in case residents needed to be evacuated from the lakeside community.
"Some have already taken shelter with relatives," De Villa said.
The Philippine Red Cross tweeted late Thursday that its volunteers drove some residents from an area of Laurel to a primary school being used as an emergency shelter.
Two coast guard trucks were deployed to Laurel to assist families wanting to leave their homes, the Philippine Coast Guard said on Facebook.
Taal is one of the most active volcanoes in a nation hit periodically by eruptions and earthquakes due to its location on the Pacific "Ring of Fire" -- a zone of intense seismic activity.
Access to the volcano island, which was once home to a community of thousands, has been prohibited since last year.