To a casual observer the southern Philippine island of Jolo, with its clear waters, white beaches and lush vegetation would appear to be a paradise.

Covering roughly 890 square kilometres (345 square miles), the volcanic island lies at the centre of the Sulu archipelago, the southernmost tip of the Philippines.

Jolo's residents largely sustain themselves through fishing and forestry.

Its population is roughly 250,000, of which 90% are Muslim, the remaining 10% Christian.

However Jolo is also home to a large number of armed gangs, bandits and pirates, including factions of the militant Islamic group Abu Sayyaf.

The Abu Sayyaf emerged in 1991 as the latest in a number of militant groups which have waged a 30-year campaign for a Muslim homeland in the south of the Roman Catholic Philippines.

Clash of cultures

The seeds of the conflict were sown in the 14th Century, when Arab traders crossed the Indian Ocean and established Islam in the southern Philippine islands.

In 1521 the explorer Ferdinand Magellan claimed the Philippines for Spain.

Westerners seized by Abu Sayyaf in 2000

This lead to more than 300 years of Spanish rule, but Spain never managed to conquer and convert the Muslim areas in the south.

In 1898 Spain sold the Philippines to the United States. American troops attempted to forcibly incorporate Muslim areas into the Philippine state.

Islamic insurgency has continued since the Philippines gained independence in 1946.

There are so many armed fighters and groups in Jolo ... it is not a peaceful place

Glenda Gloria, author

The Abu Sayyaf is believed to have once had links with Osama Bin Laden. In recent times it has concentrated on kidnapping.

One of the worst incidents came in 2000 when the guerrillas took a group of Western tourists and others hostage from a Malaysian diving resort and brought them to Jolo.

The Abu Sayyaf is thought to have earned around a $20 million ransom from that kidnapping.

Anarchy

Commentators say its current presence in Jolo is difficult to assess.

Many militants on Jolo claim to belong to the group, but most are believed to be little more than disorganised armed gangs, lacking leaders and ideology.

Jolo is base to a number of armed groups

The anarchic situation has prompted most Western governments to advise against travel to the island.

Author Glenda Gloria, who has written a book on Abu Sayyaf, told the BBC News Online:

"There are so many armed fighters and groups in Jolo it is practically impossible to walk down the street in without running into one faction or another.

"It is practically an armed province. There are lots of loose firearms in the province, it is not a peaceful place."