Metro Manila (CNN Philippines) — Incoming president Rodrigo Duterte said Thursday (May 26) he has apologized to Prime Minister Justin Trudeau of Canada for the death of a Canadian at the hands of the terrorist Abu Sayyaf Group.

“I am very sorry. I apologize for the incident,” Duterte said he told Trudeau, who called him about a week after his phone conversation with U.S. President Barack Obama.

“You can rest assured that when the time comes, we will be able to apprehend the criminals and exact justice,” he promised Trudeau.

Also read: Military captures Abu Sayyaf camp in Sulu, determined to rescue hostages

The Abu Sayyaf beheaded former mining executive John Ridsdel last month after they received no ransom. Ridsel was one of four hostages abducted by the militants in September from a resort on Samal Island off Davao City where Duterte is mayor.

The militants threatened to kill one of the three other captives — Canadian Robert Hall, Norwegian Kjartan Sekkingstad and Filipina Marites Flor — on June 13 if ransom is not paid. The group is demanding a P600 million ransom.

Also read: Abu Sayyaf releases 'final' hostage video

The Canadian government has advised its citizens against travelling to Mindanao, except the urban areas of Davao City. Canadian authorities say there is a high risk of terrorist attacks and kidnappings in the southern region.

CNN Philippines senior correspondent Ina Andolong contributed to this report.