Residents of a town at the base of Mount Pinatubo started to return to their homes as President Gloria Macapagal-Arroyo and geologists yesterday declared several districts safe from the threat of mud, following bid to drain out water in volcano crater lake on Thursday.

Raymundo Punongbayan, chief of the Philippine Institute of Volcanology and Seismology said: "The danger has passed. We have ordered everybody to go home."

Zambales Governor Vicente Magsaysay said some 9,000 residents of several Botolan districts have already returned to their homes after spending three days and two nights in the ten evacuation centres set up in safer areas in the province. Botolan has more than 40,000 residents.

"The rest, particularly those in districts which are yet to be declared safe are being prevented form returning to their homes," he said. Magsaysay identified the districts of Carael, Banagan, Capayawan, Porac, Paudpod, Baton Lapoc, Paco, San Miguel and San Juan as high risk areas located close to the Bucao River where the water drained from Pinatubo crater flows.

Phivolcs experts has not totally dismissed the possibility that the increasing water flow from a man-made canal dug at the volcano's rim would jeopardise the riverside districts of Botolan. Majority of the evacuees came from these districts.

Last Thursday, government geologists and engineers with the help of local aborigines released accumulated rain water from Pinatubo crater by breaching Maraunot Notch, the lowest portion of the volcano rim, allowing millions of tonnes of water to drain through a 150 meter long canal that leads to a natural gully.

From the gully, the water drains to the nearby Bucao River which cuts through Botolan, located some 100 km North of Manila. The water volume flowing in the canal was initially low due to the gentle slope of the canal, but after a few hours, the flow increased and Phivolcs estimated that 11 million tonnes of water drained out from the crater.

Experts want to drain out at least 25 per cent of the estimated 200 million tonnes of water in the crater in order to declare the area totally safe.

The delicate operation, the first of its kind in history, saved the entire town of Botolan from being inundated with volcanic mud in the event that heavy rains cause the volcano rim to give in.

In a press conference yesterday Arroyo commended the people who took part in the effort. "I congratulate the Philippine Institute for Volcanology and Seismology, local leaders, the military, police and the residents around Pinabubo for their cooperation in the draining operation," Arroyo said.

The president visited several evacuation centres in Botolan yesterday and made an aerial view of the volcano crater.