The Islamic State has released a video purporting to show the beheading of Japanese hostage Kenji Goto, according to SITE monitoring service.
The Japanese government was trying to authenticate the video, according to the state news agency.
The video shows a militant with a British accent beheading Goto.
The Islamic State group purportedly threatened to kll Lt. Muath al-Kaseasbeh by Thursday unless Jordan released a female al-Qaida prisoner, Sajida al-Rishawi, from death row.
Jordan has said it cannot release her without proof the pilot is alive.
The fate of the 26-year-old airman has been linked to that of Japanese journalist Kenji Goto, who also is being held by the militants.
