TOKYO (AFP) - The Japanese government said on Sunday it was "highly probable" that an Islamic State in Iraq and Syria video, in which the group said it had beheaded a second Japanese hostage, was authentic.

"After an extensive review, we believe it's highly probable" the video is real, government spokesman Yoshihide Suga said in response to a reporter's question about its authenticity.

When asked if the man in the video was 47-year-old journalist Kenji Goto, Mr Suga replied: "We think so."