MANILA, June 10 (Xinhua) -- A volcano in the central Philippine province of Sorsogon, Mount Bulusan, spewed a column of ash one kilometer long into the sky before dawn Saturday because of a build-up of steam, the Philippine Institute of Seismology and Vulcanology (PHIVOLCS) said.

    Ernesto Corpuz, PHIVOLCS' chief monitoring scientist, told the local television network ABS-CBN News that the explosion happened around 12:18 a.m. local time (06:18 GMT) emitting ash. There was no sign of lava in the 1,565-meter high volcano.

    The volcano's ash explosion Saturday was sixth time since March19 when the volcano began showing signs of renewed activity following a mild earthquake in the area. The last explosion occurred on May 31.

    The government had earlier declared the town of Casiguran, on the slope of the mountain, a "calamity" area after ash from the volcano rained down on roofs Wednesday. The authorities have also distributed face masks to residents to prevent them from inhaling volcanic ash.

    Mount Bulusan forms part of a volcanic belt in the central Bicol region which consists of active and geologically young volcanoes. Enditem