The Philippines' presumptive president-elect says he has apologized to Canadian Prime Minister Justin Trudeau over the beheading by Muslim militants of a Canadian hostage in the southern province of Sulu.

Mayor Rodrigo Duterte of southern Davao City told reporters Thursday that he apologized for the April 25 beheading of hostage John Ridsdel when Trudeau called Tuesday. He says he assured Trudeau the government will try it's best to ensure the incident is not repeated and that the perpetrators are apprehended and brought to justice.

Duterte, who won the May 9 presidential election based on an unofficial tally, is due to be inaugurated president on June 30.

Muslim militants demanding ransom have threatened to kill three more hostages in their jungle base in the southern Philippines after Ridsdel's beheading.