MANILA- The Philippines ordered the evacuation on Monday of thousands of people living near the most active volcano in the country, warning of a possible eruption within a week.

Mayon volcano, known for its near-perfect cone shape in the central Philippines, has been spewing lava and ashes that reached a height of about 100 metres (330 feet) on Monday, chief vulcanologist Renato Solidum said.

The volcano is showing increased activity and we deem it necessary to raise the alert, Solidum told Reuters, saying incandescent material had been rapidly moving up to the crater and streaking down Mayon's southeastern slope.

Joey Salceda, governor of the coconut-growing Albay province where Mayon is located, said he had ordered the evacuation of about 20,000-30,000 people living within the 6-8 km (4-5 mile) danger zone around the volcano.

We'll start evacuating the people to safer areas tomorrow (Tuesday), Salceda told reporters, requesting assistance from soldiers and police to move people from no-go zones to temporary shelter areas.

The Philippines lies on the Ring of Fire, a belt of volcanoes circling the Pacific Ocean that is also prone to earthquakes.

Mayon is the most active of 22 volcanoes in the country, having erupted more than 50 times in the last four centuries. The most destructive eruption came in February 1841 when lava flows buried a town and killed 1,200 people.

The last time Mayon erupted was in 2006. (Reporting by Manny Mogato; Editing by Raju Gopalakrishnan)