The father of a Jordanian pilot facing execution with a Japanese hostage by the Islamic State group has urged authorities to save his son "at any price".
In a video released on Tuesday, IS threatened to kill airman Maaz al-Kassasbeh and journalist Kenji Goto unless Amman releases a female jihadist being held in a Jordanian prison.
The Japanese government says it believes the deadline expires around 1400 GMT on Wednesday (0100 AEDT Thursday).
Kassasbeh's father Safi and several dozen members of the family's Karak tribe held a demonstration outside the government headquarters in Amman late on Tuesday.
They held his picture and a slogan reading: "We are all Maaz".
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"We have only one request, Maaz's return at any price," Safi was quoted by local media as saying.
"The authorities have been reassuring, saying they have had contacts about the release of our son," he said, but "we have heard nothing from them after the latest video."
A Jordanian military source said on Tuesday that the country's security services were verifying the authenticity of the recording.
The source noted that while the recording threatened Kassasbeh's life, it made no mention of freeing him in exchange for the release of Sajida al-Rishawi, who has been on death row since 2006 for her part in triple hotel bombings in Amman that killed 60 people.
Kassasbeh was captured on December 24 after his F-16 jet crashed while on a mission against the jihadists over northern Syria.
Jordan is among a number of Arab and Western countries that have joined the air raids against IS, which has seized large areas in Syria and neighbouring Iraq.
