Christian businessmen said they were planning to leave the island after Muslim leaders threatened to torch a Catholic church near the condemned mosque in the island's capital, Isabela.

According to an AFP reporter, about 100 Muslim men marched through Isabela to the home of Mayor Luis Biel, whose bodyguards fired warning shots to force them away from the building.

A local court ordered in 1989 that the 16-year-old mosque be demolished after the city government complained it was built on government land, but fears of unrest have delayed its implementation.

Mayor Biel, a Christian, said it would take affect this week, sparking complaints from prominent Muslims that it would damage relations between the two religious groups.

"According to Muslim religious leaders here, if they demolish this mosque, the rest of our members have threatened they will destroy a Catholic church," local Muslim leader Maruan Tandi said.

Hundreds of devotees attend daily prayers at the mosque, which was originally built as an Islamic study center.

Suod Omar, a Muslim scholar and organizer of the protest, said local Muslim leaders could not control the actions of all of their members.

Around 60 percent of Basilan's population is Muslim. The mostly-agricultural economy is controlled by the 40 percent of Christians.

The extremist Abu Sayyaf group, linked by Washington and Manila to Al-Qaeda, has long been active on the island, engaging in bombings and mass kidnappings of Christians and foreigners.

The protesters, some carrying placards reading "We are ready to die for Islam," also voiced anger over the publication of caricatures of the Prophet Mohammed that originally appeared in Denmark and have been widely reprinted.