TOKYO, Feb. 1 (Xinhua) -- A new video message posted online early Sunday (local time) shows that a man believed to be Kenji Goto, a Japanese man taken hostage by the Islamic State(IS) militants was beheaded.

The Japanese government said it is confirming the authenticity of the video image.

"I'm outraged by the despicable terrorist act, and I will never forgive terrorists," Japanese Prime Minister Shinzo Abe told reporters at his office after the video was posted online.

Meanwhile, U.S. President Barack Obama on Saturday condemned the "heinous murder" of Japanese hostage Kenji Goto by the Islamic State (IS) militant group, after the IS claimed in a video it posted online that it beheaded Goto.

"The United States condemns the heinous murder of Japanese citizen and journalist Kenji Goto by the terrorist group ISIL," Obama said in a statement released by the White House, using an acronym of the IS militants.

"Standing together with a broad coalition of allies and partners, the United States will continue taking decisive action to degrade and ultimately destroy ISIL," Obama added.

Obama's statement served as an acknowledgement that the video released Saturday purporting to show beheading of Goto is authentic. The White House National Security Council spokeswoman Bernadette Meehan said earlier in a statement that the United States was working to "confirm its authenticity".

The IS demanded Japan pay a ransom of 200 million U.S. dollars for the lives of two Japanese hostages of Haruna Yukawa, 42, a security contractor from Chiba Prefecture and Kenji Goto, 47, a freelance journalist from Sendai in Miyagi Prefecture. Haruna Yukawa was beheaded by the IS a week ago.