BASILAN, Philippines — The bishop in conflict-ridden Basilan province called for a cease-fire April 15 as clashes between government troops and Abu Sayyaf rebels entered its fourth day.

"I call on our brother Muslims to please respect our observance of the Holy Week," Bishop Martin Jumoad of Isabela said in a radio broadcast to his prelature.

Bishop Jumoad's appeal followed clashes that began in the town of Tipo-Tipo April 11, which claimed the lives of at least 20 people, mostly Abu Sayyaf Islamic militant fighters, and the wounding of at least 45 others, the Asian church news portal ucanews.com reported.

"Just as we respect the Ramadan, I hope also (the Muslims) will respect the Holy Week," the bishop said.

He said that despite the fighting, Catholics will continue "to profess our faith because we trust that God will provide our security."

"I continue to challenge our Catholic faithful, particularly in areas where there is danger, I challenge them to still profess our faith," Bishop Jumoad said.

Gen. Emmanuel Bautista, armed forces chief of staff, said there will be no letup in government operations against the rebels even during the observance of Holy Week.

"We will continue to run after the (Abu Sayyaf). There is no letup in Basilan or in Sulu," Bautista told reporters in Zamboanga after visiting wounded soldiers in a military hospital April 15.

The fighting in Tipo-Tipo has already resulted in the evacuation of some 1,500 people.

Laisa Alamia, executive secretary of the Autonomous Region in Muslim Mindanao, said the villages of Silangkong and Baguindan in Tipo-Tipo have turned into "ghost towns."