A Japanese journalist waits near the Turkish-Syrian border's Akcakale border crossing, near Sanliurfa, Turkey, on Thursday. According to local media, Islamic State may release Japanese hostage Kenji Goto in a possible prisoner exchange.

Reuters/Tokyo

The wife of a Japanese journalist thought to be held by Islamic State insurgents in Syria urged the Japanese and Jordanian governments to work for his release shortly before a deadline set by his captors expired.

"I fear that this is the last chance for my husband, and we now have only a few hours left to secure his release and the life of (Jordanian air force pilot) Lieutenant Muath al-Kasaesbeh," Kenji Goto's wife Rinko said in a statement to Reuters and other media.

"I beg the Jordanian and Japanese government(s) to understand that the fates of both men are in their hands," she said in her first public comments since Goto appeared in a purported Islamic State video on January 20 with fellow captive Haruna Yukawa, whose apparently beheaded body appeared in a subsequent video on Saturday.

The statement appeared about an hour before the captors' deadline of sundown in Mosul, Iraq - around 11.30 pm Japan time. Goto announced the Islamic State deadline in an audio message earlier on Thursday that the Japanese government said appeared genuine.

Goto said that the pilot would be killed immediately if Jordan did not release would-be suicide bomber Sajida al-Rishawi, a death-row prisoner, by the deadline.

In a previous statement, Goto had said his own life depended on the woman's release. Although Jordan said it was willing to swap Rishawi for the pilot, a government minister said an hour before the deadline passed that Amman was still waiting for proof that the pilot was alive.

Goto's wife said she had been "working tirelessly behind the scenes" for his release since his capture on October 26 as he sought the release of Yukawa, who was seized in August.

"I have not spoken out until now as I have been trying to protect my children and family from the media attention Kenji's plight has created around the world," Rinko wrote.

"My husband and I have two very young daughters. Our baby girl was only three weeks old when Kenji left. I hope our oldest daughter, who is just two, will get to see her father again.

"I want them both to grow up knowing their father. My husband is a good and honest man who went to Syria to show the plight of those who suffer," she said.