LEGAZPI CITY (Philippines) • Intense lava fountains shot like fireworks up to 700m above Mayon, the Philippines' most active volcano, showering debris, turning the skies dark and spreading fear among anxious residents yesterday.

More than 40,000 people have fled since smoke and ash started spewing from the mountain earlier, with scientists warning of the danger of an explosive eruption and the authorities urging people not to be complacent, Agence France-Presse reported.

Mayon's rain of fine debris brought daytime darkness in some areas. "People got scared. The kids did not understand what was happening... suddenly it got dark and you could not see who you were with," Mr Danny Garcia, a spokesman for Albay province where Mayon is located, told AFP.

The summit of the mountain was shrouded by a dense column of steam and hot rocks, creating fanciful shapes in the sky.

"The explosion looks like a cauliflower or an octopus," said Mr Ed Laguerta, Mayon's resident volcanologist from the Philippine Institute of Volcanology and Seismology. "Hot ash ascends and since the volcano is conical, the pyroclastic flow seems to be the tentacles," he added, referring to a mix of hot lava, ash and volcanic gas flowing down the volcano's flanks.

Mayon, a near-perfect cone located about 330km south-east of the capital Manila, is considered the most volatile of the Philippines' 22 active volcanoes.

The authorities have ordered people to leave a danger zone stretching 8km from the volcano and yesterday shut down schools and businesses in Albay province.

Airports in the cities of Legazpi and Naga and at the nearby island of Masbate have been closed, while small aircraft have been banned from flying near the volcano. Some highways have also been closed, with ash showers making driving in some areas nearly impossible, the provincial government said.

Regional disaster officials advised people to wear face masks, goggles or glasses and to stay indoors to avoid inhaling sulphur dioxide gas. Volcanologists told residents to heed warnings from the authorities even in towns not yet affected by ash falls.

Meanwhile, in a travel advisory yesterday, the Ministry of Foreign Affairs said Singaporeans should defer non-essential travel to the volcano and nearby areas, due to a possible major eruption.

It also said Singaporeans in Albay province and nearby regions should monitor the local news closely, take all necessary precautions for their personal safety, and heed the instructions of the local authorities.

They should get comprehensive travel and medical insurance and be familiar with the terms and coverage, the advisory added.