SHAFAQNA (International Shia News Association) A video has been released online purporting to show the beheading of Japanese hostage Kenji Goto by Islamic State militants.
The video comes less than a week after news of the beheading of another Japanese man, Haruna Yukawa.
Mr Goto, 47, is a well-known freelance journalist and film-maker who went to Syria in October, reportedly to try to secure Mr Yukawa’s release.
Japan, as well as the US, UK and France, has condemned the killing.
The video, which bears the same symbols as previous IS videos, shows a militant with a British accent beheading Mr Goto.
Japanese government spokesman Yoshihide Suga said Japan was “outraged” by the video, adding that the cabinet was meeting to decide a response to it.
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Prime Minister Shinzo Abe said Japan “would not give in to terrorism” and said he would increase aid to the Middle East.
He added Japan would work with the international community to bring those responsible for Kenji Goto’s apparent murder to justice.
Mr Goto’s mother Junko Ishido said she “can’t find the words” to describe his death, saying he had gone to Syria out of “kindness and courage”.
His brother Junichi told Japanese broadcaster NHK TV: “I was hoping Kenji would come back alive to thank everyone who had supported him.”
“I am filled with sadness he couldn’t do it.”
President Obama said in a statement the US condemns “the heinous murder” of Mr Goto.
Britain and France have also condemned the apparent killing.
UK Prime Minister David Cameron called IS “the embodiment of evil, with no regard for human life”.
Japanese officials had been working with Jordan to secure the release of Mr Goto and a Jordanian pilot, Moaz al-Kasasbeh, who was shot down over Syria in December.
However, earlier on Saturday they said negotiations had become deadlocked.
An IS video released on Tuesday said Mr Goto had “only 24 hours left to live” and Mr Kasasbeh “even less”.
They later gave a deadline of sunset on Thursday for a deal by which Mr Goto would be freed in return for Jordan releasing captured Iraqi militant Sajida al-Rishawi.
But the deal may have been complicated by Jordan’s demand that Mr Kasasbeh also be released.
The latest video gave no mention of Mr Kasasbeh’s fate: his family said they were praying he was safe.
IS had initially demanded a $200m (£130m) ransom for the two Japanese hostages.