Japan's Prime Minister says his country won't bow to extremism - following a $200 million ransom demand from Islamic State.

A video released by the group threatens to kill two Japanese hostages unless the money's received within 72 hours.

In the video, a black-clad militant brandishing a knife addresses the camera in English as he stands between two hostages wearing orange jumpsuits.

"You now have 72 hours to pressure your government into making a wise decision by paying the $200m to save the lives of your citizens," he says.

The footage, identified as being made by the militant group's al Furqan media arm and posted on militant websites, also sees the militant criticising the Japanese government's support for US-led airstrikes against IS.

The militant who appears in the video appears to be the same one involved in the beheadings of other captives by IS.

Speaking in a British accent, he says: "To the prime minister of Japan: Although you are more than 8,000 and 500 kilometres (5,280 miles) from the Islamic State, you willingly have volunteered to take part in this crusade.

"You have proudly donated $100m to kill our women and children, to destroy the homes of the Muslims."

The two hostages are identified as Kenji Goto Jogo and Haruna Yukawa.

In August, a Japanese citizen believed to be Mr Yukawa - a private military company operator - was kidnapped in Syria.

Mr Goto is a freelance journalist who went to report on Syria's civil war last year.

IS has seized swathes of territory across Iraq and Syria to form an Islamic Caliphate.

Videos featuring a British-accented jihadi were published showing the murders of US hostages James Foley and Steven Sotloff and British hostages David Haines and Alan Henning.