At least five people were killed and 30 injured Sunday following an explosion outside a Catholic church in Cotabato City, Philippines.

Archbishop Orlando Quevedo of the Archdiocese of Cotabato condemned the attack outside the Cathedral of the Immaculate Conception as people were leaving Mass, calling it a “sacrilege”.

“The church they attacked is a place of refuge, even for criminals,” he told the local Manila Bulletin. “People were worshipping when the bomb went off. This is not just a crime, this is a sacrilege.”

Pope Benedict XVI also condemned the violence and prayed for the victims.

"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," the Pope told pilgrims in St Peter's Square.

According to Cotabato City Mayor Muslimin Sema, authorities arrested a male suspect minutes after the blast.

While some have accused the 11,500-strong Moro Islamic Liberation Front for the attack, a spokesman for the group has denied involvement and also condemned the bombing.

He said the rebels would not do anything to foment a religious war though the militant group has been fighting to establish a separate Islamic state.