AMMAN/TOKYO (Reuters) - Jordan said on Thursday it was still holding an Iraqi would-be suicide bomber as a deadline passed for her release set by Islamic State militants who threatened to kill a Jordanian pilot unless she was handed over by sunset.

An audio message purportedly from a Japanese journalist also captured by the insurgents said the pilot would be killed unless Jordan freed Sajida al-Rishawi, who is on death row for her role in a 2005 suicide bomb attack that killed 60 people in Amman.

The message postponed a previous deadline set on Tuesday in which the journalist, Kenji Goto, said he would be killed within 24 hours if Rishawi was not freed.

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 U.S.-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, which has seized large tracts of Syria and Iraq.

“We have not received any evidence that Kasaesbeh is alive. This is what we asked and have not received any proof,” Momani said.

He said separately that Jordan was coordinating with Japanese authorities in an effort to secure the release of Goto, a veteran war reporter also being held by the radical Islamists.

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 0930 ET.

The implication that the Jordanian pilot would not be part of an exchange deal has left Jordan in a difficult position.

Slideshow ( 7 images )

Any swap that left out the pilot would be deeply unpopular after officials insisted he was their priority, and could leave Amman subject to further demands from the militants.

But refusing the insurgents’ ultimatum could heighten domestic opposition to Jordan’s unpopular role in the U.S.-led military campaign against Islamic state.

Protests have erupted in Karak, hometown of the pilot, who is from an important Jordanian tribe that forms the backbone of support for the Hashemite monarchy.

Slideshow ( 7 images )

TEST FOR ABE

The hostage crisis is the biggest diplomatic test for Japanese Prime Minister Shinzo Abe since he took office in 2012 pledging to play a bigger role in global security.

Jordanian comments have raised concerns in Japan that Goto might no longer be part of any deal between Amman and Islamic State.

“I hope the negotiations materialize,” Goto’s mother, Junko Ishido, told reporters at her Tokyo home. “I don’t want to think about it,” she said, when asked what she would do if negotiations failed.

Abe said the government was making every effort to ensure Goto’s early release.

He reiterated that Japan would not give in to terrorism and Tokyo would keep cooperating with the international community.

“If we are too afraid of terrorism and give in to it, this will give rise to fresh terrorism against Japanese and it will become a world in which the will to carry out despicable violence has its own way,” Abe told parliament. “Such a thing is totally impermissible.”

The hostage crisis erupted after Abe, while on a tour of the Middle East, announced $200 million in non-military aid for countries opposing Islamic State, but his government has rejected any suggestion it acted rashly and stressed the assistance was humanitarian.

Goto went to Syria in late October. According to friends and business associates, he was attempting to secure the release of Haruna Yukawa, his friend and fellow Japanese citizen who was captured by Islamic State in August.

In the first video purportedly of Goto, released last week, a black-clad masked figure with a knife said Goto and Yukawa would be killed within 72 hours if Japan did not pay Islamic State $200 million.

A video on Saturday appeared to show Goto with a picture of a decapitated Yukawa, saying his captors’ demands had switched to the release of al-Rishawi. Tuesday’s video featured an audio track over a still picture that appeared to show Goto holding a picture of a now bearded Kasaesbeh.