The Philippine authorities vowed to crush those behind twin bombings that killed at least 20 people and injured over 80 who had been attending a Sunday mass in the country’s restive southern island of Mindanao. 

The attack came just six days after a referendum on autonomy for the mainly Muslim region returned an overwhelming “yes” vote, and was one of the deadliest in recent years in an area long plagued by conflict, insurgencies, Islamist terrorist activities and military crackdowns. 

The first explosion occurred inside the Cathedral of Our Lady of Mount Carmel in Jolo, the capital of Sulu province, while the second blast struck outside near the entrance as panicked worshippers fled and security forces arrived to help.  

The death toll, which was initially reported as 27 but later revised down to 20, included at least five security personnel as well as multiple civilians. 

At least 21 people were killed in the attackCredit:
Nickee Butlangan/AFP

On Monday, Islamic State’s East Asia branch claimed responsibility for the attack, according to the US-based SITE Intelligence Group, which tracks the online activities of extremist groups.

The claim has not been verified by the Philippine authorities and a military report contradicted Isil claims that two suicide bombers had detonated the blasts.

On Sunday, suspicion had fallen quickly on the terrorist Abu Sayyaf group, which has been linked to both Al Qaeda and Isil, and has carried out some of the most heinous crimes in the Philippines in recent years including bombings and the beheading of local and foreign hostages. 

Arnel dela Vega, chief of the Philippine military’s Western Mindanao Command, said Abu Sayyaf remained the primary suspect for Sunday’s attack, based on previous threats. But he cautioned that this conclusion was subject to "further assessment and validation,” reported Rappler. 

Soldiers guard a Catholic Church where two bombs exploded in Jolo, Sulu province Credit:

Others speculated that the twin bombings could be related to the ratification this week of a devolution plan for the Muslim minority who are concentrated in the Mindanao region of the Catholic-majority Philippines. 

Plans for greater autonomy for Muslims had inspired hopes of bringing development, jobs and peace to an island regarded as one of Asia’s poorest regions, and where about 150,000 people have been killed during an anti-government rebellion that began in the 1970s.

Jolo stood out in its failure to endorse the autonomy vote on Monday, sparking fears of reprisals by Islamist groups. 

Soldiers in front of a Catholic Church where two bombs exploded in Jolo, Sulu province Credit:

Hermogenes Esperon, the national security adviser, said in a statement that the attack appeared to be connected to the plebiscite, while the Moro Islamic Liberation Front, one of the groups pushing for autonomy, said the perpetrators wanted to put “religious colour” to the vote. 

Salvador Panelo, the presidential spokesman, added: “The enemies of the state have boldly challenged the capability of the government to secure the safety of the citizenry in that region,” reported Reuters.  

“The armed forces of the Philippines will rise to the challenge and crush these godless criminals.” 

Mark Field, minister of state for Asia and the Pacific, condemned the horrific attack. “Our prayers are with all the victims and their loved ones. The UK stands with the Philippines against hatred and terror,” he said on Twitter.

The UK foreign office advises “against all travel to western and central Mindanao and the Sulu archipelago because of terrorist activity and clashes between the military and insurgent groups.”

Western governments have welcomed the autonomy pact. They worry that small numbers of Islamic State-linked militants from the Middle East and Southeast Asia could forge an alliance with Filipino insurgents and turn the south into a breeding ground for extremists.