“Tokyo Police referred two people to prosecutors for planning to travel to Syria as an anti-government group fighter,” a police spokesman told AFP.

The spokesman added three other people were also referred to prosecutors but gave no further details.

One of the five, according to local media, is a 31-year-old former student who planned to travel to Syria in 2014.

He told police he wanted to join IS to work as a fighter.

The other four include veteran freelance journalist Kosuke Tsuneoka and Islamic law scholar Ko Nakata, who the student apparently consulted about travelling to Syria.

Early this year the Japanese government ordered Tsuneoka to surrender his passport as he prepared to leave for Yemen.

The move came amid debate in Japan about whether journalists should be prevented from going to war zones after the capture and release of a Japanese reporter in Syria last year.