ABOARD AIR FORCE ONE (AFP) - US President Barack Obama strongly condemned on Saturday the killing of a Japanese hostage by the Islamic State in Iraq and Syria (ISIS) group, though the execution has not yet been independently confirmed.
"The United States strongly condemns the brutal murder of Japanese citizen Haruna Yukawa by the terrorist group," Obama said in a statement, referring to the ISIS group, as he flew to India for a visit.
Japanese officials were still working to verify a video posted online claiming that one of two men held hostage by Islamic State militants had been executed.
Images appear to show Japanese hostage Kenji Goto holding a photograph of Yukawa's slain body.
"We renew our call for the immediate release of Kenji Goto and all other remaining hostages," Obama added in the statement.
"We stand shoulder to shoulder with our ally Japan and applaud its commitment to peace and development in a region far from its shores."
The video was not posted on any of the ISIS group's official channels and it does not bear the group's black and white flag.
The purported execution of Yukawa is also not shown.
The two hostages went into Syria last year and had been out of contact for months.
Goto, born in 1967, is a freelancer who set up a video production company named Independent Press, in 1996. It feeds video documentaries on the Middle East and other regions to Japanese television networks, including public broadcaster NHK.
British Prime Minister David Cameron said the apparent murder was a reminder of the group's 'murderous barbarity'.
"The reported brutal murder of Haruna Yukawa and the further threats made by ISIL are yet another reminder of the murderous barbarity of these terrorists," Cameron said in a statement issued by his Downing Street office.
He offered his "thoughts and prayers" to Yukawa's family and said that Britain "stands in solidarity with the Japanese people at this difficult time."
He also backed Japanese counterpart Shinzo Abe's "firm stance" in dealing with ISIS, which demanded a US$200 million (S$270 million) ransom for the hostages' release.
Tokyo is under pressure from Britain and the United States to resist the group's cash demands, as both countries have a policy of never paying ransoms.