About 8,000 residents were evacuated after a small active volcano near Mla spewed a massive cloud of ash on Sunday that drifted across the city, as experts warned of another possibility of "hazardous explosive eruption."
People residing near the Taal volcano and other high-risk areas were asked to leave by the National Disaster Risk Reduction and Management Council after it suddenly shot a column of ash and steam as high as 15 kilometres (9 miles) into the sky, Al Jazeera reported.
Taal, one of the world's smallest active volcanoes, sits in the middle of a lake about 70km (45 miles) south of the centre of Mla.
Authorities said there was a risk an eruption could cause a tsunami in the lake.
"Taal is a very small volcano but a dangerous volcano," said Renato Solidum, head of the Philippine Institute of Volcanology and Seismology. "It is unique because it is a volcano within a volcano."
The institute raised the danger level posed by the volcano to 4 out of a possible 5 - meng "hazardous explosive eruption is possible within hours to days". The highest alert is level 5 issued when a magmatic eruption is underway.
The Philippines lies on the Ring of Fire, a belt of volcanoes circling the Pacific Ocean that is also prone to earthquakes.
One of the most active volcanoes in the Philippines, Taal has erupted more than 30 times in the past five centuries, most recently in 1977.
Meanwhile, the spewing ash forced the cancellation of 172 flights in and out of the international airport on Sunday. Authorities said flights would also be suspended on Monday because there was ash on the runway.
President Rodrigo Duterte's office further ordered the suspension of government work in the capital and of all school classes in Mla and other areas affected by the ash. Health officials warned of possible breathing problems for people with respiratory ailments and urged the public to stay indoors and use dust masks when going out.
( With inputs from ANI )