MANILA—President Rodrigo Duterte on Tuesday said suicide bombers were responsible for the blasts that hit a Catholic church in Jolo and killed at least 21 people.

Citing a briefing from the military, Duterte said the perpetrators were a couple.

He said the female suicide bomber apparently skirted security personnel in the area, because “it’s not the norm” for females to get frisked.

“Kasi babae, wala namang . . . it’s not the norm in this country na magkapkap ka ng babae sa simbahan,” Duterte told reporters in a chance interview.

The President, however, said there is “conflicting” information about the nationalities of the suicide bombers.

Duterte made the statement, even as the military already discounted the possibility that the attack on the church was a case of suicide bombing.

• 'No suicide bomber': Woman left bomb inside Jolo church- military

He acknowledged that the Philippine government had received warnings from the Indonesian government about a possible terror attack in Sulu.

“We were already warned, not only by Indonesia, by the rest of the — kaya may umiikot na military doon,” he said.

Duterte denied there was a lapse in security.

“I don’t think so. Walang lapses doon, because the other bomber was outside. There was no reason for him to be frisked,” Duterte said, referring to the companion of the supposed female suicide bombber.

“Either he was just passing by before blowing himself up, ang problema ang babae was wearing a cross pa.”

The military on Tuesday released a surveillance footage showing a man, supposedly showing Alias Kamah, brother of slain bandit leader Surakah Ingog, triggering the explosive device.

Kamah, a known bombmaker, ran from the church and out of the video's frame with several cohorts, moments after the explosion, said Col. Gerry Besana, spokesperson of the military's Western Mindanao Command.

The group was also behind several kidnapping and extortion cases in Sulu, he said.

The Islamic State group on Monday claimed credit for the attack, saying two suicide bombers detonated a belt of explosives, according to US-based SITE Intelligence Group, which monitors jihadist activities.

The military was not discounting this claim but said the Ajang-Ajang, a subgroup of the bandit Abu Sayyaf Group, could be behind the blast.

Even though the investigation into the bombing has not yet been concluded, Duterte said he has no doubt that the Abu Sayyaf was behind the blasts.

“I have no doubt. That is what the military told me and that is what the police relate to me, and I’m guided by what the government workers would tell me,” he said.

The Jolo bloodshed came a week after a majority of voters approved the creation of the Bangsamoro, a new region giving Muslims in the south more control over their own affairs.

Sulu, which includes the remote island of Jolo, voted against creating the new region, but the province will still be part of the Bangsamoro because voters from the current autonomous region were in favor of it.

On Tuesday, police said the twin blasts was a "clear act of terror" and had nothing to do with the plebiscite.