People walk past a TV screen broadcasting a news program about Islamic State hostages Jordanian air force pilot Muath al-Kasaesbeh (back top 3rd L) and Japanese journalist Kenji Goto (back top 2nd L), along a street in Tokyo January 29, 2015. [Photo/ Agencies]

The Islamic State (IS) militant group claimed in a video it posted online late Saturday night that it beheaded the other Japanese hostage Kenji Goto.

According to site monitoring service, IS released the video that purportedly showed the beheading of the Japanese captive.

In the video, a hooded man stood over Goto, and held a knife to his throat. The following footage showed a head placed on a body.

However, the authenticity of the video and the fate of Goto cannot be verified at the moment.

If proven to be true, it means that Japan has failed in rescuing both of its nationals held by the extremist militant group.

On Friday, Japan said the collective efforts by Japan and Jordan to save the captured Japanese journalist and the Jordanian pilot are "deadlocked" and the situation remains highly unpredictable.

"The situation is deadlocked," Japan's deputy foreign minister, Yasuhide Nakayama, said in Jordon late on Friday, according to Japanese public broadcaster NHK.

The IS has demanded that it would release the Japanese hostage in exchange for a would-be suicide bomber being held in Amman by sunset on Thursday.

According to a recently published audio message purportedly from Goto, he said the Jordanian pilot would be killed if Jordan did not free Sajida al-Rishawi, jailed for her role in a 2005 suicide bomb attack that killed 60 people in Amman.

In the audio clip, the IS said if Sajida is handed over, the Japanese hostage will be released.

In a statement on Thursday, the Jordanian army said the priority is the safety of the pilot, who was captured by the IS late last year after his plane crashed in Raqqah in Syria.

Jordanian authorities said they were willing to hand over the Iraqi suicide bomber if the Jordanian pilot is released and demanded a proof that he is still alive.

A week ago and in another online video, Japanese hostage Kenji Goto said Haruna Yukawa, another Japanese held by IS, was beheaded.

Earlier, the IS militants demanded that they wanted the Japanese government to pay 200 million U.S. dollars so that the captured Japanese nationals could be released.

The amount of the ransom equaled to that of the assistance Japanese Prime Minister Shinzo Abe promised during his recent tour in Egypt to offer to regional countries in their battles against the IS militants.