From prime minister to ordinary people, Japanese responded with shock today at a video purportedly showing one of two Japanese hostages of the extremist Islamic State group had been killed.

With national attention focusing on efforts to save the other hostage, 47-year-old journalist Kenji Goto, some also criticised Prime Minister Shinzo Abe's drive for a more assertive Japan as responsible for the hostage crisis.

A somber Abe appeared on Japanese public broadcaster NHK early today demanding the militants release Goto unharmed.

He said that the latest video was likely authentic, although he added that the government was still reviewing it. He offered condolences to the family and friends of Haruna Yukawa, a 42-year-old adventurer taken hostage in Syria last year.

Abe declined to comment on the message in the video, which demanded a prisoner exchange for Goto. He said only that the government was still working on the situation, and reiterated that Japan condemns terrorism.

"I am left speechless," he said. "We strongly and totally criticise such acts."
Yukawa's father, Shoichi, told reporters he hoped "deep in his heart" that the news of his son's killing was not true. "If I am ever reunited with him, I just want to give him a big hug," he said.

The Associated Press could not verify the contents of the video message, which varied greatly from previous videos released by the Islamic State group, which now holds a third of both Syria and Iraq.

Patrick Ventrell, a spokesman for the White House National Security Council, said US intelligence officials were also working to confirm whether it was authentic.

Criticism of Abe has touched on his push for an expanded role for Japan's troops, one that has remained strictly confined to self-defense under the pacifist constitution written after the nation's defeat in World War II.

The threat from the Islamic State group coincided with Abe's trip to the Middle East, where he announced USD 200 million in humanitarian aid to the nations fighting the militants.

Reflecting widely held sentiments here, Jun Hori, an independent journalist, bemoaned Abe's directly mentioning the Islamic State in announcing the aid.

The Islamic State addressed Abe and cited that same figure as ransom demand in its video Tuesday that threatened to behead Yukawa and Goto within 72 hours.

Japanese government spokesman Yoshihide Suga said the audio was still being studied, but there was no reason to deny the authenticity of the video