Japan's Prime Minister Shinzo Abe has said that the "credibility" of a video announcing the execution of a Japanese hostage by the Islamic State (ISIS) is "high", AFP reports.
"We have been looking into its authenticity, but unfortunately at the moment we cannot help saying its credibility is high," he said on the public network NHK on Sunday morning (local time).
"Considering the unbearable pain and sorrow that his family must be feeling, I am speechless," Abe said.
"Such act of terrorism is outrageous and impermissible, it causes me nothing but strong indignation," he added. "I condemn it strongly and resolutely."
The government will continue analyzing the images to fully confirm the authenticity of the video, Abe said.
The nearly three-minute recording, posted online Saturday, shows a still image of Kenji Goto holding an apparent photograph of Haruna Yukawa's slain body, with an audio recording in which Goto spoke of ISIS’s demand for a prisoner exchange to guarantee his release.
It was not posted on any of the group's official channels and it does not bear their black and white flag. The purported execution of Yukawa is also not shown.
In a video released this past Tuesday, ISIS threatened to kill the two Japanese hostages unless Tokyo pays a $200 million ransom within 72 hours.
World leaders condemned the murder of Yukawa and demanded that ISIS release the other hostage immediately.
"The United States strongly condemns the brutal murder of Japanese citizen Haruna Yukawa by the terrorist group," said U.S. President Barack Obama in a statement.
"We renew our call for the immediate release of Kenji Goto and all other remaining hostages," he added. "We stand shoulder to shoulder with our ally Japan and applaud its commitment to peace and development in a region far from its shores."
British Prime Minister David Cameron also condemned ISIS, noting that the video is a reminder of the group's "murderous barbarity."
"The reported brutal murder of Haruna Yukawa and the further threats made by ISIS are yet another reminder of the murderous barbarity of these terrorists," Cameron said in a statement issued by his Downing Street office.