Islamic State has claimed responsibility for two deadly blasts that tore through a Roman Catholic cathedral in southern Philippines yesterday.

At least 20 people were killed and 80 more injured, when the first blast went off in or near the Jolo cathedral during Sunday mass.

The second blast occurred outside the cathedral, timed to go off as military and rescue workers arrived at the scene.

The bombing came “less than a week after voters' decisive approval of giving Muslims in the south more control over their own affairs, which sparked hopes of quelling long-time separatist violence”, Channel NewsAsia said.

“The enemies of the state have boldly challenged the capability of the government to secure the safety of the citizenry in that region,” said Philippines government spokesman Salvador Panelo.

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

Jolo “has long been troubled by the presence of Abu Sayyaf militants,” The Guardian says, “who are blacklisted by the United States and the Philippines as a terrorist organisation because of bombings, kidnappings and beheadings”.

Defence Secretary Delfin N. Lorenzana said in a statement he condemned the bombing, adding that he has directed troops to “heighten their alert level” and secure places of worship and public spaces.