Sekkingstad was released after almost a year in captivity while Canadian hostages were earlier beheaded.
The Abu Sayyaf armed group has released three Indonesian hostages in the southern Philippines a day after freeing a Norwegian captive held for a year and repeatedly threatened with beheading.
Sunday’s release – negotiated by the Moro National Liberation Front rebels – took place on the island of Jolo in Sulu province.
Norwegian Kjartan Sekkingstad, who was let go on Saturday, described the ordeal as “devastating”, carrying a backpack with a bullet hole as a reminder of a near-death experience, which included the decapitations of two Canadians kidnapped with him.
The three Indonesian hostages were identified as Lorence Koten, Theorus Kopong, and Emanuel Arakain. They were abducted from the Sabah state of Malaysia in July.
Sekkingstad, 56, said after his release he was treated “like a slave” by the group, which is linked to Islamic State of Iraq and the Levant (ISIL, also known as ISIS).
“[I was] always kept in the dark and given misinformation, like, not reliable information, psychological pressure like: ‘You gonna be beheaded [on] such and such a date’ – always threats hanging over your head,” he said.
Abu Ramie, a spokesman for Abu Sayyaf, said the group received a $638,000 ransom for Sekkingstad’s release. The government of the Philippines said it did not pay the group and was unaware of any payment made by other parties.
Sekkingstad was abducted from a luxury tourist resort in September 2015 alongside a Filipina woman, who has already been freed, and the two Canadian men.
Duterte has deployed 7,000 troops to Sulu to go after Abu Sayyaf.
The United States and the Philippines have separately blacklisted the group as a “terrorist” organisation for bombings, extortion, kidnappings for ransom, and beheadings of locals and foreigners.