MANILA, Philippines (AP) — Human rights groups asked the Philippine president Wednesday to retract a threat to order airstrikes against tribal schools he accused of teaching students to become communist rebels, warning such an attack would constitute a war crime.

U.S.-based Human Rights Watch said international humanitarian law "prohibits attacks on schools and other civilian structures unless they are being used for military purposes," adding that deliberate attacks on civilians, including students and teachers, "is also a war crime."

Left-wing Rep. Emmi de Jesus of the Gabriela Women's Party asked Duterte to retract the threat, saying government troops may use it as a pretext to attack indigenous, or Lumad, schools and communities in the country's south which have come under threat from pro-military militias in recent years.

Angered by recent communist rebel attacks on government forces, including a road gunbattle last week that wounded five members of his elite presidential guards, Duterte has called off peace talks with the Maoist guerrillas and threatened their perceived sympathizers.

In a televised news conference he called late Monday shortly after delivering his annual state of the nation address, Duterte condemned the insurgents for destroying bridges and torching schools in the countryside but said the insurgents were sparing Lumad schools which he alleged were operating under rebel control without government permits.

"Get out of there, I'm telling the Lumads now. I'll have those bombed, including your structures," the president said. "I will use the armed forces, the Philippine air force. I'll really have those bombed ... because you are operating illegally and you are teaching the children to rebel against government."

"By calling for an attack on schools, Duterte is directing the military to commit war crimes," Carlos Conde of the Human Rights Watch said in a statement.

Conde urged Duterte to sign a 2015 international political statement, the Safe Schools Declaration, that commits government to support the protection of students, teachers and schools in times of armed conflict.

Duterte ascended to the presidency last year after campaigning on his extra-tough approach on crime as a prosecutor and later as mayor of southern Davao city. He has remained popular despite thousands of deaths in his nationwide anti-drug crackdown, and his continuing popularity and the ineffective opposition have apparently emboldened him.

On Monday night, Duterte also called for abolishing the Commission on Human Rights, an independent agency created under the constitution to investigate rights violations. He demanded that the commission and the government Ombudsman, who investigates officials for corruption and other infractions, route requests to investigate police and military personnel through him and laid down conditions under which he would allow those investigations.

Duterte said if the Ombudsman failed to address atrocities committed by insurgents on government forces, "so that you can get the truth and the whole story, then do not investigate my army and police."