Philippine militant group Abu Sayyaf: Who are they?
The police find has led to speculation the group was involved in Monday’s abduction of two Canadian tourists, a Norwegian resort manager and a Filipina on Samal island, more than 500 kilometres (311 miles) away.
Here are answers to some key questions about the group and their activities.
Who are they?
The loosely organised band emerged in the early 1990s — with funding provided by a brother-in-law of Osama bin Laden — as an even more violent offshoot of a decades-old Muslim insurgency that has wracked the southern region of Mindanao since the 1970s.
The group strikes terror well beyond its bases on Jolo and Basilan islands and has been blamed for the worst bomb attacks in the country. It claimed the firebombing of a ferry off Manila Bay in 2004 that killed more than 100 people. The group has also abducted Western tourists and missionaries in the Philippines and Malaysia, sometimes beheading captives if ransoms are not paid.
What is their agenda?
Recruiting mostly from impoverished locals, Abu Sayyaf professes to fight for an independent Islamic state in Mindanao, using million-dollar ransom proceeds from dozens of kidnappings to finance their operations and buy weapons.
The group has harboured foreign militants from Jemaah Islamiyah, which seeks to set up a caliphate across Southeast Asia and is blamed for the deadly 2002 Bali bombings. Last year Abu Sayyaf also pledged allegiance to the Islamic State group in Syria and Iraq.
Why does the threat persist?
From 2002-2014 about 500 US special forces advisers trained and provided intelligence to Philippine troops fighting Abu Sayyaf, which led to the killing or arrest of many militant leaders.
US assistance was scaled back last year, on grounds the joint effort had degraded the militants’ fighting capability and left it as “disorganised groups resorting to criminal undertakings to sustain their activities”. But this offers little comfort to locals still at risk.
How dangerous are they?
Many Western and other embassies routinely issue warnings to their citizens in the Philippines against travel to most of the country’s Muslim southern region on the risk of abduction or due to fresh bomb threats.
However the group has at times struck in areas previously thought safe, such as the Manila Bay ferry attack and the 2000 kidnapping of Western tourists on Sipadan resort in Malaysia.
Will a Muslim peace deal help?
President Benigno Aquino’s government last year signed a peace deal with the Moro Islamic Liberation Front (MILF), the country’s largest guerrilla group, aimed at ending decades of insurgency that has impoverished its Muslim south.
The MILF says the deal would prevent the further radicalisation of Filipino Muslims and undercut Abu Sayyaf’s base. However a bill implementing the main points of the agreement has stalled in parliament.