Japanese freelance photographer Yuichi Sugimoto (R) shows a mandate letter issued by Foreign Minister Fumio Kishida during a news conference at the Foreign Correspondents' Club of Japan in Tokyo February 12, 2015. [Photo/Agencies]

TOKYO - A Japanese photojournalist whose passport was confiscated by the government ahead of a planned trip to Syria said his case sets a dangerous precedent for other journalists travelling abroad to report on foreign wars.

In an unprecedented move, Japan's Foreign Ministry seized freelance photographer Yuichi Sugimoto's passport this month as it steps up security after the execution of two Japanese nationals captured by Islamic State militants.

"I am concerned that this case might set a very bad precedent in this country. In the future, other journalists might have orders issued and their passports confiscated," Sugimoto told a news conference on Thursday.

"The freedom to report, the freedom to cover news might be harmed," he said.

Sugimoto, who has covered wars in Bosnia, Afghanistan, Iraq and Syria for the past two decades, had originally planned to travel later this month to the town of Kobani, which was retaken last week by Syrian Kurds backed by US air strikes.

He said ministry officials and policemen visited his apartment in Niigata, northern Japan, this month and told him he would be arrested if he did not hand in his passport.

"I asked them when I would be able to get my passport back and they said they could keep it for an unlimited time," said Sugimoto. Officials also did not tell him how he could have his passport returned, he said.

Chief Cabinet Secretary Yoshihide Suga said this week the government wants to respect the freedom of journalists to report but decided it must fulfil its duty to ensure the safety of Japanese nationals.