The Philippines' most active volcano on Sunday spewed thick ash and steam for a second day as thousands of residents fled their homes near the rumbling mountain, officials said.

The second phreatic eruption at Mayon Volcano in Albay province, 330 kilometres south of Manila, lasted approximately five minutes on Sunday morning, the Philippine Institute of Volcanology and Seismology (Phivolcs) said.

"The event produced a greyish steam and ash plume that was largely obscured by summit clouds," the agency said in a bulletin. "Sulfurous odour was detected and rumbling sounds were heard by residents."

Phivolcs raised the alert on Mayon Volcano to level 2 on Saturday after the first phreatic eruption, which created an ash column with an approximate height of 2,500 metres.

"The public is strongly advised to be vigilant and desist from entering the 6-kilometre-radius permanent danger zone to minimize risks from sudden explosions, rockfall and landslides," the agency said.

More than 2,200 residents from the towns of Guinobatan, Camalig and Anoling have fled their homes since Saturday, according to Chief Inspector Arthur Gomez, a spokesman for the provincial police.

The displaced residents have taken shelter in schools turned into evacuation centres, Gomez said.

The 2,472-metre volcano has erupted about 50 times since 1616. Its last deadly eruption was in May 2013, in which five hikers were killed and seven other people injured.

Mayon's most violent eruption was in 1814, when more than 1,200 people were killed and a town was buried in volcanic mud. An eruption in 1993 killed 79 people.

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