People stage a rally near the Prime Minister's official residence in Tokyo on Wednesday to support Japanese hostage Kenji Goto who has been kidnapped by the Islamic State group. The jihadist group threatened to kill Goto and a Jordanian pilot within 24 hours unless Amman frees a jailed female militant. Photo: AFP

Jordan said on Wednesday it was willing to hand over an Iraqi woman jailed for her role in 2005 suicide bomb attacks if a Jordanian pilot captured by Islamic State (IS) was released.

Government spokesperson Mohammad al-Momani made no mention of Japanese hostage Kenji Goto, a veteran war reporter who is also being held by the militant group.

"Jordan is ready to release prisoner Sajida al-Rishawi if the Jordanian pilot Lieutenant Muath al-Kasaesbeh is released and his life spared," Momani was quoted on state television as saying.

Kasaesbeh was captured after his jet crashed in northeastern Syria in December during a bombing mission against IS.

His fate was thought to be tied to that of Goto after a video was released on Tuesday purporting to show the Japanese national saying he had just 24 hours to live unless Jordan released al-Rishawi.

The voice on the video said Kasaesbeh had a shorter time to live. Japan confirmed the existence of the video at 11 pm (1400 GMT) on Tuesday.

Momani said Jordan's priority was to secure the release of the pilot, who hails from an important Jordanian tribe that forms the backbone of support for the Hashemite monarchy.

Al-Rishawi has been held in Jordan over her role in triple hotel suicide bombings that killed 60 people in the capital Amman.

In Japan, a spokesperson for Prime Minister Shinzo Abe's office said he had no immediate comment on the Jordanian statement.

There has been a flurry of unconfirmed reports in the Japanese media that a swap deal involving Goto might be in the works.

Goto's mother, speaking before Jordan made its announcement, appealed for his life. "Please save Kenji's life. I call on you to work with all your strength in negotiations with the Jordanian government," Junko Ishido said in a letter to Abe that she read out at a news conference.

Abe said the latest video was "despicable." He called on Jordan to cooperate with Japan in working for Goto's quick release, but vowed Tokyo would not give in to terrorism.

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 in August.

In the first of three videos purportedly showing 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 IS $200 million.

A video on Saturday appeared to show Goto with a picture of a beheaded 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 bearded Kasaesbeh.