TOKYO, Feb. 1 -- Japanese Prime Minister Shinzo Abe on early Sunday morning harshly condemned the purported killing of Kenji Goto, following the latest video message uploaded by the militant group Islamic State shows the beheading of a man suspected to be the captured Japanese national.

"It is an outrage and entirely unacceptable. We will do everything in our power to find the perpetrators and bring them to justice. We will not give in to terrorism," the prime minister reiterated in no uncertain terms.

In a one-minute video clip purportedly posted by IS, a man believed to be Goto appears kneeling on the ground, wearing orange jumpsuit. A man clad in black, wielding a knife and wearing a mask, is stood to the rear of the hostage.

The masked man said because"Japanese Prime Minister Shinzo Abe 's reckless decision to take part in an un-winnable war, his knife will not just slaughter Goto, but will also carry on and cause carnage wherever Japanese people are found."

After the video was posted on-line, Abe told reporters at his office that he was utterly"outraged by the despicable terrorist act,"adding that he would never give into terrorists. The prime minister said that Japan would redouble its efforts to work with the international community and not tolerate such acts of terrorism.

Abe added that the tragic slayings of the two Japanese hostages by IS would not deter the Japanese government from providing financial aid to countries fighting against IS and other terrorist organizations, and would in fact be looking to increase its level of humanitarian aid for such activities.

Early Sunday morning both Japanese and U.S. officials were trying to confirm the authenticity of the video, although sources close to the matter have suggested the video is authentic based on previous videos.

Japanese officials had been working with Jordon to secure the release of Goto, since a video released on Tuesday said he had only 24-hours left to live. Meanwhile, the Jordanian government was trying to broker a deal that would see Goto and an IS-held Jordanian pilot, Moaz al-Kasasbeh, who's F-16 fighter jet had been shot down in December, exchanged for an Iraqi would-be suicide bomber, Sajida, who was convicted for her role in a series of bombings in the Jordanian capital of Amman in 2005 which killed around 60 people.

Since Tuesday, the government had remained extremely tight- lipped over developments regarding Goto, with Abe and other senior officials in Tokyo declining to comment on speculation over a possible prisoner swap.

Abe's top spokesperson Chief Cabinet Secretary Yoshihide Suga has told reporters that the government believed Goto was still alive and was seeking cooperation from Jordan and other relevant governments, religious and tribal leaders to secure his release.