MANILA - The Philippines put civil defense personnel on alert for possible deadly volcanic mudflows as a tropical storm began bearing down on a volcano that has been spitting ash for weeks.

Civil defense reports said a ferry sank in rough seas off Sorsogon province, leaving at least two missing and feared dead. More than 40 others were rescued and rushed to hospital, the reports said.

Before leaving on a visit to Europe, President Gloria Arroyo said the civil defense office has prepared contingency plans in case rain from the storm mixes with ash on the slopes of Bulusan volcano in Sorsogon to form deadly mudflows.

Arroyo said two C-130 cargo planes, eight helicopters including the presidential helicopter and a train were ready to travel to the Bicol peninsula south of Manila to help people who might be displaced.

Arroyo said vulcanologists did not believe that the 1,565-meter (5,134-foot) Bulusan mountain was likely to erupt in the next few days but they should prepare for such contingencies.

More than 2,000 people have already evacuated their homes around the volcano for fear of mudflows, the civil defense office said.

There have been periodic ash emissions at Bulusan since March but these have become more frequent this month.

The Philippine vulcanology institute said it had detected four volcanic earthquakes in the past 24 hours. It warned that prolonged rain "might trigger life-threatening mudflows."

The institute reiterated that residents should stay at least four kilometers (2.5 miles) from the crater.

The government weather station said the tropical storm, locally named as "Domeng", was heading northwest towards Bicol at 19 kilometers (12 miles) per hour.

The eye of the storm, packing maximum winds of 90 kilometers (56 miles) per hour, passed Biliran island and was expected to pass beside the Bicol peninsula on Monday morning. It was not expected to hit the region directly.

Sea travel in the area around the storm has been restricted, stranding over a thousand people at various ports, the civil defense office said.

The second level of a four-step storm alert has been raised over parts of Bicol and the neighboring islands and provinces. A first-level storm alert has been raised in provinces just south of Manila.