MANILA- Philippine authorities started evacuating about 50,000 people from around the country's most active volcano on Tuesday as it spewed burning mud and rocks.

Mayon volcano, famed for its near-perfect cone shape in a coconut-growing region of the central Philippines, started to release lava early this week and vulcanologists are expecting a major eruption in the next few days.

We are in the process of evacuating nearly 10,000 families around the 6-8 km (4-5 mile) danger zone around the volcano, Cedric Daep, head of Albay province's public safety office, told reporters.

Daep said the fleeing residents were being temporarily housed in school buildings and public gymnasiums, where local government officials set up food and relief centres.

We have enough food for all these people for only a month, Daep said, adding humanitarian and non-government groups have pledged to send food, water, medicines and blankets.

Renato Solidum, the country's chief vulcanologist, told Reuters on Monday the alert level around Mayon had been raised to number 3, indicating volcanic materials were now near the top of the crater and incandescent materials were detaching.

Level 4 means an eruption is imminent while Level 5 means an eruption is in progress.

We've been monitoring a high-level of unrest and there could be an hazardous explosion coming, Solidum said.

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)