Japan condemns 'outrageous' hostage murder

Prime Minister Shinzo Abe has demanded the immediate release of Yukawa's fellow captive, freelance journalist Kenji Goto

Prime Minister Shinzo Abe today branded the murder of a Japanese hostage by Islamic State militants "outrageous and impermissible" and demanded the release of a second hostage, amid a growing global chorus of revulsion.

Abe spoke as the grieving father of self-employed security contractor Haruna Yukawa said he had gone "totally blank" since learning of his son's execution, announced in a video posted online by the militants late yesterday.

Abe, speaking to public broadcaster NHK, said he was "speechless" at the "unbearable pain and sorrow" that Yukawa's family were feeling.

"Such act of terrorism is outrageous and impermissible, it causes me nothing but strong indignation," he said.

"I condemn it strongly and resolutely," he said as he demanded the immediate release of Yukawa's fellow captive, freelance journalist Kenji Goto.

Shoichi Yukawa told of the horror of realising the threats to kill his son had been carried out.

"I thought 'Ah, this finally happened' and was filled with regret," he said in a statement to media.

"I went totally blank, I was only sorry... I had no words to say," he said. "In my mind I wish very much that this wasn't true."

US President Barack Obama led the condemnation of the Islamic State group's "brutal murder" of Yukawa. British Prime Minister David Cameron decried the movement's "murderous barbarity", and French President Francois Hollande labelled it a "barbaric assassination".

Japan would continue analysing the images to fully confirm the authenticity of the video, said Abe, but the "credibility" of the footage was "high".

The recording, which lasts nearly three minutes, shows a still image of Goto holding what appears to be a photograph of Yukawa's slain body.

It was posted with an audio recording in which a man claiming to be Goto blames Abe for his fellow captive's death after he failed to pay a $200 million ransom.

The voice also reveals a new demand from the militants for the release of Sajida al-Rishawi, a female militant now held in Jordan, in exchange for Goto's life.