Manila, Mar 9 (IANS): Philippine authorities on Tuesday raised the alert level for Taal volcano to 2, saying it is showing "increasing unrest".

"This means that there is (a) probable magmatic activity that may or may not lead to an eruption," Renato Solidum, director of the Philippine Institute of Volcanology and Seismology, said in a local radio interview.

The institute said it raised the alert level from 1, or low-level unrest, to 2, or increasing unrest, after detecting 28 "volcanic tremor episodes, four low-frequency volcanic earthquakes, and one hybrid earthquake at shallow depths of less than 1.5 km beneath the volcano in the past 24 hours", reports Xinhua news agency.

"Volcanic tremors have increased seismic energy compared to previously recorded episodes and ranged between three to 17 minutes in duration," the institute said in a statement, adding the number of volcanic tremor events has increased to 866 since the onset of increased activity on February 13.

The institute added that 141 low-frequency volcanic earthquakes have occurred within one-km depth beneath the volcano and immediate vicinities.

"Overall, seismic activity in the past month indicates increased magmatic and hydrothermal activity at shallow depths beneath Taal volcano island," the institute said.

The institute urged people to stay away from the island, reminding the villagers that the island is a permanent danger zone.

"Entry into the island, especially the vicinities of the main crater and the (tourist trail), must remain strictly prohibited," the institute said.

Taal volcano, 66 km south of Manila, last erupted in January 2020.

An active earthquake zone, the Philippines has frequent seismic activity due to its location along the Pacific "Ring of Fire".

At least 24 active volcanoes dot the Philippine archipelago.