Five people have died and seven others have been injured after a volcano in the central Philippines erupted unexpectedly on Tuesday.

Disaster management officials say the dead were among a group of 20 foreign tourists climbing Mount Mayon in the central province of Bicol when it erupted.

Two helicopters have been sent to the top of the volcano to rescue the surviving tourists.

It is believed the group was about 1.5 kilometres away from the crater when Mayon spewed a thick column of ash 500 metres into the air.

Volcanologists say steam explosions occur regularly and they don't expect another major eruption following today's event.

Residents in towns around Mount Mayon said they were surprised by the sudden activity, which came as many were having breakfast.

Mayon, about 330 kilometres southeast of Manila, is the largest of the Philippines' 22 active volcanoes.

It has erupted 48 times in recorded history,

In 1814, more than 1,200 people were killed when lava flows buried the town of Cagsawa.

In December 2009 tens of thousands of villagers were displaced when Mayon spewed ash and lava.

The volcano also erupted in August 2006. There were no direct deaths caused by the explosion, but the following December a passing typhoon unleashed an avalanche of volcanic mud from its slopes that killed 1,000 people.