Five people were killed and 46 others injured in a bomb explosion Sunday morning in front of a Roman Catholic cathedral in the southern Philippines.

People stand beside debris caused by a bomb explosion just outside the Immaculate Conception Cathedral in Cotabato City. (Associated Press)

The bomb detonated near the Immaculate Conception Cathedral in Cotabato City as churchgoers were attending mass, witnesses said.

Police believe the improvised explosive was set off remotely by cellphone and was hidden in a row of food stalls selling roast pig.

A local nurse said at least seven of the wounded were in critical condition and needed surgery.

Police arrested one man seen using a phone during the explosion. He was carrying three identification cards with different names, Cotabato Mayor Muslimin Sema said.

Maj.-Gen. Alfredo Cayton blamed the 11,500-strong Moro Islamic Liberation Front for the attack. The group is based in Mindanao province where the blast took place and has been targeted by a months-long military offensive in nearby Maguindanao province and outlying regions.

"Nobody has the motive, the capability and the track record to carry out this terrorist attack except" the group, Cayton told The Associated Press.

Col. Jonathan Ponce said the group has carried out similar attacks in recent weeks.

Rebel spokesman Eid Kabalu denied his group was involved in the bombing.

The Moro Islamic Liberation Front has fought for decades for an independent Islamic state in the southern Philippines.

Pope Benedict XVI condemned the attack.

"While I pray to God for the victims of this ignoble gesture, I raise my voice to condemn yet again the recourse to violence, which is never a worthwhile way to solve existing problems," Benedict told pilgrims in St. Peter's Square.

With files from The Associated Press