Japan isn't commenting on a reported ransom demand for a Japanese freelance journalist who has been missing since summer in Syria.

A government spokesman said Thursday that Japan is doing its utmost to deal with the situation, but wouldn't go into specifics.

The France-based nonprofit group Reporters Without Borders says it has learned that those holding journalist Jumpei Yasuda have started a countdown for a ransom payment, and are threatening to kill him or sell him to another militant group.

It is calling on the Japanese government to do everything possible to obtain his release.

Another freelance journalist was among two Japanese killed by the Islamic State group in Syria early this year in a hostage crisis that gripped Japan for several weeks.