The Islamic State jihadist group released a new video on Sunday purporting to show captured Kurdish peshmerga fighters paraded through Iraqi streets in cages.
The video shows 21 captives presented as 16 peshmerga fighters, two Iraqi army officers and three policemen from Kirkuk, a city about 240 kilometres (150 miles) north of Baghdad.
The captives, in orange jumpsuits with their heads lowered, are led to cages in a square surrounded by concrete walls and masked ISIS fighters carrying pistols.
A bearded man in a white turban warns the peshmerga against fighting ISIS.
Then the caged captives are shown being paraded through the streets on the back of pick-up trucks, as dozens of residents and armed men look on.
Later, some of the prisoners are interviewed by an Islamist holding a microphone bearing ISIS's logo.
The date and location is not specified in the video, but Kurdish sources told AFP it was filmed a week earlier in the main market of Hawija, an ISIS-held town some 50 kilometres (30 miles) from Kirkuk.
The video does not contain any explicit threats to the captives but they are shown at the end kneeling before masked men holding automatic weapons or pistols, with an implied threat of the fate that awaits them.
The video also features images from previous ISIS videos, including of the killing of Jordanian pilot Maaz al-Kassasbeh, who was burned alive in a cage, and the beheadings of 21 Coptic Christians, mainly from Egypt, in Libya.
A peshmerga commander in Kirkuk, General Hiyowa Rash, told AFP that the peshmerga hostages had been captured on January 31 "when Kurdish fighters repelled a terrorist attack by ISIS targeting Kirkuk."
ISIS seized swathes of Syria and Iraq last year, declaring an Islamic "caliphate" and committing widespread atrocities.