MANILA, May 25 (Xinhua) -- The Philippines' most active volcano Mayon is at a "moderate level of unrest" anew, prompting the authorities to warn residents to stay out of the six-kilometer danger zone due to possible "sudden explosions."

"Mayon Volcano's seismic monitoring network recorded two volcanic earthquakes during the past 24 hours," the Philippine Institute of Volcanology and Seismology (Phivocsl) said in its Friday bulletin.

The 2,460-meter (8,070-ft) cone-shaped volcano is located in Albay province approximately 300 kilometers southeast of Manila on the island of Luzon.

Phivocsl observed that "a degassing event occurred at 7:58 a.m. on Thursday that produced a 300 meter-tall brownish ash plume that drifted southwest."

It added, that "a moderate emission of white steam-laden plumes that rose 300 meters from the summit before drifting southwest, west-southwest and west-northwest was observed throughout the day. Fair crater glow from the summit could be observed at night."

The alert level for Mayon remains at two on a scale of five, indicating the volcano is at moderate level of unrest.