MANILA -- The twin bombings that hit a church in Jolo on Sunday was a "clear act of terror" and had nothing to do with the plebiscite on the Bangsamoro Organic Law (BOL) held just days earlier, the Philippine National Police (PNP) said Tuesday.

The blasts, which left 21 dead and at least 80 injured, were likely perpetrated by the Ajang-Ajang faction of the bandit Abu Sayyaf group, said PNP spokesperson Senior Supt. Bernard Banac, citing evidence police have gathered so far.

"Based on our investigation, there is no connection between the two. This thing that happened, the bombings, is just a clear and simple act of terrorism. It has nothing to do with the plebiscite," he told ANC's Early Edition.

Banac also belied claims by international terror network Islamic State that its suicide bombers were responsible for the twin blasts. He said the blasts were caused by electronically-triggered improvised explosives.

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The incident happened amid the continuing implementation of martial law over all of Mindanao, an extension of an initial declaration prompted by the 5-month siege of Marawi City in 2017.

In a plebiscite on the Bangsamoro law held on Jan. 21, the Autonomous Region in Muslim Mindanao (ARMM) and Cotabato City voted in favor of establishing a new Bangsamoro region with greater autonomy in Mindanao. Isabela City voted against joining this region.

Though part of the ARMM, the province of Sulu where Jolo town is located voted against the establishment of the new Bangsamoro region. The province's governor also questioned this law before the Supreme Court.

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The BOL is the enabling law of a 2014 peace deal between the government and the formerly secessionist Moro Islamic Liberation Front, the country's largest Moro rebel group. The legislation is seen to bring lasting peace in the long restive south.

On February 6, towns in Lanao del Norte and villages in North Cotabato will vote on whether or not to join the new Bangsamoro region. Banac said the police will intensify their checkpoints on this day to prevent another bombing incident.

"Our security preparations are already in place. We will be focusing on heightened and intensified checkpoints to make sure people will not carry firearms or even explosives," he said.

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