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.

READ MORE: Abu Sayyaf frees Norwegian hostage Kjartan Sekkingstad

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.

Sekkingstad, left, and Canadian Robert Hall, right, were abducted from a high-end tourist resort in September 2015 along with two other people [Reuters]

Sekkingstad, newly shaved but looking gaunt in a loose polo shirt, thanked all those who worked for his freedom.

“I am very happy to be alive and free,” he said. “It’s a beautiful feeling.”

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.

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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.

Abu Sayyaf demanded a huge ransom for the release of the foreigners, and released videos in which they threatened the captives in a jungle clearing where they displayed ISIL-style black flags.

In April and June, the Canadians – John Ridsdel , 68, and Robert Hall , 67 – were beheaded after ransoms were not paid, while the Filipina, Marites Flor, was released.

After they decapitated Ridsdel, Sekkingstad was threatened by the fighters, who repeatedly told him, “You’re next.”

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.