BEIRUT (AFP) - The Islamic State in Iraq and Syria (ISIS) said on Sunday that it executed one of two Japanese hostages it has been holding, in an apparent beheading branded "outrageous and unforgivable" by Japanese Prime Minister Shinzo Abe.
The claim came a day after the release of a video announcing the murder of security contractor Haruna Yukawa, 42, by the militant group which has beheaded five Western hostages since August last year.
It sought to raise the pressure on Japan by saying the fate of the other captive, freelance journalist Kenji Goto, 47, depended on the release of an Iraqi would-be female bomber who is on death row in Jordan.
"The Islamic State has carried out its threat... it has executed Japanese hostage Haruna Yukawa after the expiry of the deadline given," the group said on its Al-Bayan radio.
"The second hostage is calling on his relatives to put pressure on the (Japanese) government for the release of our sister Sajida al-Rishawi, held in the jails of the oppressors in Jordan, in exchange for his release."
Rishawi was sentenced to death by a Jordanian court in September 2006 in connection with triple hotel bomb attacks in Amman the previous year that killed 60 people. Her name emerged on Saturday in an ISIS video that showed Goto holding what appears to be a photograph of Yukawa's slain body.
The video came with an audio recording in which a man claiming to be Goto says Yukawa was killed because Japan had failed to pay a US$200 million (S$268.9 million) ransom within a 72-hour deadline announced last Tuesday.
Abe branded the murder of Yukawa as "outrageous and unforgivable" and called for Goto's immediate release. "I condemn it strongly and resolutely," said the Japanese leader.
The video also unleashed a tide of global revulsion. The United Nations Security Council on Sunday condemned the murder and called for the immediate release of Goto.
"The Security Council... strongly condemned the heinous and cowardly act," a statement read.
"This crime is, yet again, a tragic reminder of the increasing dangers people face every day in Syria, including journalists," the Security Council said. "It also once again demonstrates the brutality of (the ISIS group), which is responsible for thousands of abuses against the Syrian and Iraqi people."
The 15 countries demanded the immediate release of Goto and all hostages still being held by the ISIS, the "Al-Nusra Front and all other individuals, groups, undertakings and entities associated with Al-Qaeda."
US President Barack Obama had earlier condemned the "brutal murder" and offered Abe condolences while expressing his solidarity with the people of Japan.
British Prime Minister David Cameron decried the ISIS' "murderous barbarity", and French President Francois Hollande labelled it a "barbaric assassination".
Germany and the EU also condemned the killing by ISIS, an extremist Sunni Muslim group which activists say carries out near-daily executions, often beheadings, in areas under its control.
The group, which originated in Iraq and appeared in Syria's civil war in spring 2013, holds swathes of Syria and Iraq where it has declared an Islamic "caliphate".
Since then it has committed atrocities including the beheadings of two US reporters, an American aid worker and two British aid workers.