MANILA (AFP) - The Philippines has stockpiled food supplies in case of evacuations after a volcano emitted ash and smoke six times in recent weeks, officials said on Sunday.

In addition to the emergency food packs, the authorities are closely watching communities near the Bulusan volcano 390km south-east of Manila, said presidential spokesman Herminio Coloma.

The latest emissions came on Friday, with two other eruptions earlier last week. "The government continues to monitor the behaviour of Mount Bulusan... so we can safeguard the welfare of about 34,000 affected residents in 22 villages and five towns," said Mr Coloma.

The government volcano monitoring institute said that so far, the emissions have been caused by groundwater mixing with hot rocks inside the 1,565m volcano.

These "phreatic eruptions" have sent ash and smoke into the air, covering the volcano's slopes and nearby towns, said Mr Winchelle Ian Sevilla, the officer heading a team monitoring Bulusan.

He said that as long as people stay out of the 4km "danger zone" around Bulusan, they would not be hurt by any falling rocks.

Aircraft have also been warned to avoid Bulusan in case of a sudden ejection of ash.

Despite the activity, Mr Sevilla said there was no sign magma was rising inside the volcano, indicating there was no impending eruption of lava.

Bulusan's last destructive eruptions were from November 2010 to February 2011, eventually forcing hundreds of villagers to evacuate. There were no reports of casualties or damage.

The Philippines is located in the seismically-active Pacific "Ring of Fire" and has over 20 active volcanoes.