DAVAO, Philippines (Reuters) - Philippine police blamed Islamic State-linked rebels on Saturday for a bombing that killed 14 people in President Rodrigo Duterte’s hometown and dealt a blow to the firebrand leader’s bloody crackdown on narcotics and militancy.

Investigators said Abu Sayyaf, a southern Philippine group notorious for acts of piracy, kidnappings and beheadings, had claimed responsibility for Friday’s night bombing at a Davao street market, although police said they were still trying to authenticate the claim.

The attack rattled the normally peaceful home city of Duterte, who typically spends his weekends there, some 980 kilometers away from the capital Manila. He was in Davao at the time of the bombing but far from the site of the blast outside a hotel where he often holds meetings.

National police chief Ronald Dela Rosa said the bomb was home-made and fragments of mortar were found at the site, where two “persons of interest” had been caught on camera.

The bomb was likely to have been planted by Abu Sayyaf, he said, to divert the military’s attention from its operations to flush them out of their strongholds on the islands of Basilan and Jolo.

The military on Tuesday agreed to deploy a further 2,500 troops to carry out Duterte’s order to “destroy” Abu Sayyaf.

“From being offensive, they want us to be defensive,” Dela Rosa told a news conference late on Saturday.

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Duterte canceled what would have been his first overseas visit on Saturday, to Brunei, and declared a nationwide “state of lawlessness” to deal with what he called an extraordinary security situation.

“I must declare a state of lawless violence in this country,” Duterte told reporters after visiting the blast site, where he assured the public that martial law had not been imposed.

“I have this duty to protect this country,” he said.

POWERFUL ENEMIES

Police and military promised to act in accordance with his “state of lawlessness”, although there was some confusion about what that actually entailed. Duterte’s office said it referred to a constitutional clause that states the president has full power over the armed forces.

The bombing came as the abrasive former prosecutor wages war on narcotics kingpins and street dealers, Islamist rebels and corrupt bureaucrats, scoring big points in opinion polls but at a risk of making powerful enemies.

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Rumors have swirled of a plot to assassinate Duterte, 71, which he has shrugged off as part of his job. The talk has been fueled by his controversial crackdown on drugs that saw him elected by a huge margin, but condemned by human rights groups and the United Nations.

More than 2,000 alleged drug pushers and users have been killed since Duterte’s June 30 inauguration. Critics are alarmed at the sheer number whose deaths have been attributed to vigilantes, and the president and police chief’s apparent support for it.

Duterte’s tough stance on crime has ensured Davao has been spared the kind of violence that has dogged other parts of Mindanao, a large island province where several Islamist militant groups operate, including Abu Sayyaf.

Abu Sayyaf, which means “bearer of the sword”, has previously used an Islamic State flag in some of its propaganda videos and runs what is among Asia’s most lucrative kidnap rackets.

It has this year decapitated two Canadian hostages and held Norwegian, Indonesian, Malaysian and Japanese citizens.

The group has long been a thorn in the side for the military and has used its ransom earnings to entrench its network and invest in modern weapons, boats and radar technology.

The White House offered condolences and assistance to the Philippines, a key regional ally. Duterte is expected to meet U.S. President Barack Obama in Laos next week, when he attends a the Association of South East Asian Nations (ASEAN) and East Asia Summits.