The mother of a Japanese hostage held by Islamic State group extremists appealed publicly to Japan's leader to save her son Wednesday after his captors purportedly issued what they said was a final death threat.

Junko Ishido, mother of journalist Kenji Goto, read to reporters her plea to Prime Minister Shinzo Abe, which she said she sent after both Abe and the main government spokesmen declined to meet with her because their schedules were full.

"Please save Kenji's life," Ishido said, begging Abe to work with the Jordanian government until the very end to try to save Goto.

"Kenji has only a little time left," she said.

The effort to free Goto and a captured Jordanian pilot, Lt. Mu'ath al-Kaseasbeh, gained urgency with the release of an apparent ultimatum late Tuesday from the Islamic State group.

In the message, the extremists said the two hostages would be killed within 24 hours — late Wednesday night Japan time — unless Jordan frees Sajida al-Rishawi, an Iraqi woman sentenced to death in Jordan for her involvement in a 2005 terrorist attack on a hotel that killed 60 people.

Jawad al-Kaseasbeh, an uncle of the captured pilot, said Wednesday that the family had seen no signs of progress toward his possible release. "We are still waiting," al-Kaseasbeh told The Associated Press by phone.

Yasuhide Nakayama, a Japanese envoy for the crisis in the Jordanian capital, Amman, said only that talks on securing Goto's release were "ongoing."

"I don't have any information that I can share with you at the moment," he said when asked about possible "good developments."

"There are various reports but I don't know at all if they are true," he said.

"We will never give up until our Japanese hostage Mr. Goto comes back," Nakayama said. "We will pray for him. We will never give up."

In Tokyo, chief government spokesman Yoshihide Suga said he had no new developments to report.

"As the government, we are doing everything we can," he told reporters, appearing grim and weary.

Abe earlier expressed outrage at the threat.

"This was an extremely despicable act and we feel strong indignation. We strongly condemn that," Abe said. "While this is a tough situation, we remain unchanged in our stance of seeking help from the Jordanian government in securing the early release of Mr. Goto."

The Jordanian pilot's father, Safi al-Kaseasbeh, beseeched his government "to meet the demands" of the Islamic State group.

"All people must know, from the head of the regime to everybody else, that the safety of Mu'ath means the stability of Jordan, and the death of Mu'ath means chaos in Jordan," he told The Associated Press.

About 200 of the pilot's relatives protested outside the prime minister's office in Amman, chanting anti-government slogans and urging that it meet the captors' demands.

The chairman of the foreign affairs committee of Jordan's parliament, Bassam Al-Manasseer, told Bloomberg News that the country was in indirect talks with the militants through religious and tribal leaders in Iraq to secure the hostages' release. He said Jordan and Japan would not negotiate directly with the Islamic State group and would not free al-Rishawi in exchange for Goto only.

Jordan's main ally, the U.S., opposes negotiating with extremists, but Manaseer's comments were the strongest suggestion yet that Japan and Jordan might be open to a prisoner exchange.

The militants reportedly have killed one Japanese hostage, Haruna Yukawa, and the crisis has stunned Japan.

Although many in Japan are critical of the two men for going to Syria, Goto's friends and supporters have launched a social media campaign calling for his release.

Tuesday's video resembled a message released over the weekend that purportedly withdrew a demand for $200 million in ransom for Goto and Yukawa made in an earlier message.

The AP could not independently verify the videos released Saturday and Tuesday. They lack the logo of the Islamic State group's al-Furqan media arm. But some militant websites affiliated with the Islamic State group referenced the latest video and posted links to it Tuesday.

The latest message condemns Jordan for not releasing al-Rishawi, saying that unless she is freed within 24 hours, the pilot, followed by Goto, will be killed. It says it is the group's last message.

"I have only 24 hours left to live and the pilot has even less," it says.

A release of al-Rishawi would be a major propaganda coup for the Islamic State and would allow the group to reaffirm its links to Al Qaeda in Iraq.

Messages from other Western hostages held by the group have been read by the captives on camera and it is unclear why the group released only a recording and still picture.

Al-Kaseasbeh, 26, was seized after his Jordanian F-16 crashed near the Islamic State group's de facto capital of Raqqa in December. He is the first foreign military pilot they have captured since a U.S.-led coalition that includes Jordan began an aerial campaign against the Islamic State group in August.

This is the first time that the group has publicly demanded the release of prisoners in exchange for hostages. Previous captives may have been released in exchange for ransom, although the governments involved have refused to confirm any payments were made.

Goto, a freelance journalist, was caught in October in Syria, apparently while trying to rescue Yukawa, 42, who was taken hostage last summer.

The mother of another Jordanian prisoner, Ziad al-Karboli, said her family was told the Islamic State group also wants his release as part of a swap, but it is unclear if that was related to a possible deal involving the Japanese hostage.

Al-Karboli, an aide to a former Al Qaeda leader in Iraq, was sentenced to death in 2008 for killing a Jordanian citizen.