Amman (AFP) - Jordan's military said on Friday that it was still awaiting proof that a warplane pilot threatened with execution by the Islamic State group is safe.

IS had vowed to kill F-16 airman Maaz al-Kassasbeh by sunset on Thursday unless Amman handed over an Iraqi female jihadist in return for captured Japanese journalist Kenji Goto.

Jordan has demanded evidence that the pilot who crashed in Syria on December 24 is still alive before freeing would-be suicide bomber Sajida al-Rishawi who is on death row.

"Jordan has so far received no information that proves the pilot Maaz al-Kassasbeh is safe and sound," military spokesman Mamdoh al-Ameri told AFP.

Jordan has offered to free Rishawi, who was convicted for her part in triple-hotel bombings in Amman in 2005 that killed 60 people, if IS releases the pilot.

The government has been under heavy pressure at home and from Japan -- a major aid donor -- to save Kassasbeh as well as Goto.

Kassasbeh's father Safi has begged authorities to save his son while many Jordanians have taken to social media to say the pilot's life is more important than that of "terrorist" Rishawi.

On Friday, Kassasbeh told AFP that the family "did not receive any information yet about the fate of our son".

"We believe in God and we will accept whatever he has in store for us," said Safi Kassasbeh.

While IS threatened Kassasbeh's life, it was not clear from its latest message if the jihadist group was ready to free him as part of an exchange.

IS had set the Thursday sunset deadline for Rishawi to be released at the Turkish border in return for Goto but there was no news of a swap by nightfall.

On Thursday, government spokesman Mohammad al-Momani said Rishawi was still in Jordan and would only be released if IS gave it "proof of life".

He made no mention of Goto, whose wife Rinko broke her silence with an emotional appeal to Tokyo and Amman to save her husband.

"My husband is a good and honest man who went to Syria to show the plight of those who suffer," she said.

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"I beg the Jordanian and Japanese governments to understand that the fates of both men are in their hands."

Japan, which plays no military part in the fight against IS, was thrust onto the front line last week when a video appeared in which Goto and Haruna Yukawa, a self-described contractor, were seen kneeling in the desert.

A masked, knife-wielding militant said Tokyo had 72 hours to pay a $200 million (175 million-euro) ransom if it wanted to spare their lives.

When that deadline expired, new pictures appeared to show Yukawa had been beheaded, and a voice identifying itself as Goto demanded the release of Rishawi.