THE fate of two Japanese hostages held by Islamic State militants remains unknown although unconfirmed reports on Twitter state they have been executed.

The militants had demanded $200 million in return for the lives of 47-year-old freelance journalist Kenji Goto Jogo and Haruna Yukawa, who had travelled to Syria to train with fighters.

We have intercepted multiple ISIS communications claiming Japanese hostages have been killed. #GhostSec #OpISIS pic.twitter.com/JO3xh35J6h — DIGITΛSHΛDØW (@DigitaShadow) January 23, 2015

The 72-hour time limit the militants had put on the ransom demand was due to expire at 2.50pm Tokyo time on Friday, CNN reported.

CNN also stated that an IS spokesman had told a Japanese broadcaster that the group would issue a statement “soon”, but no statement arrived.

There has been no official confirmation of the Twitter reports, which CBS News characterised as ‘unconfirmed Twitter chatter’.

Goto’s mother had made a televised plea for her son’s life.

“Time is running out. Please, Japanese government, save my son’s life,” said Junko Ishido.

“My son is not an enemy of the Islamic State,” she said in a tearful appearance in Tokyo.

Ishido said she was astonished and angered to learn from her daughter-in-law that Goto had left less than two weeks after his child was born, in October, to go to Syria to try to rescue the other hostage, 42-year-old Haruna Yukawa.

“My son felt he had to do everything in his power to try to rescue a friend and acquaintance,” she said.

In very Japanese fashion, Ishido apologised repeatedly for “all the trouble my son has caused.”

Lacking clout and diplomatic reach in the Middle East, Japan had scrambled for a way to secure the release of the two men,

Japan has joined other major industrial nations of the Group of Seven in opposing ransom payments. US and British officials also said they advised against paying.