A relative of Jordanian pilot Muath al-Kasaesbeh, who was captured by Islamic State after his plane crashed in northeastern Syria in December during a bombing mission against them, holds a picture of him at the family's headquarters in the city of Karak January 29, 2015. [Photo/Agencies]

The hostage crisis comes as Islamic State, which has already released videos showing the beheadings of five Western hostages, is coming under increased military pressure from US-led air strikes and by Kurdish and Iraqi troops pushing to reverse the Islamist group's territorial gains in Iraq and Syria.

About an hour before the new deadline was due to pass, government spokesman Mohammad al-Momani said Jordan was still holding Rishawi.

"We want proof ... that the pilot is alive so that we can proceed with what we said yesterday -- exchanging the prisoner with our pilot," Momani told Reuters.

The pilot, Muath al-Kasaesbeh, was captured after his jet crashed in northeastern Syria in December during a bombing mission against Islamic State.

Momani said separately that Jordan was coordinating with Japanese authorities in an effort to secure the release of Goto, a veteran war reporter.

Goto's wife urged both governments to work for her husband's release, saying in a statement to Reuters and other media that she feared this was his last chance.

In the latest audio recording purportedly of Goto, he said that Kasaesbeh would be killed "immediately" if al-Rishawi was not at the Turkish border by sunset on Thursday, Iraq time, ready to be exchanged for the Japanese hostage.

That was some time around 1430 GMT on Thursday.