Russia has arrested a Japanese journalist on the far east island of Sakhalin and accused him of spying, in the latest sign of rising tensions between Moscow and Tokyo.

Russian foreign ministry spokesperson Maria Zakharova identified the reporter as Yuki Imai, from the Hokkaido Shimbun newspaper, adding that he had been accused of “conducting espionage activities on Russian territory”.

Imai, a reporter at the newspaper’s bureau in the city of Yuzhno-Sakhalinsk on Sakhalin, was reportedly preparing to return to Japan when he was arrested for allegedly collecting information on Russia’s defence capabilities, according to Russia’s Tass news agency.

Russia’s FSB security agency claimed the journalist had intended to pass the information on to Japanese intelligence.

The FSB published a video showing masked officers storming a hotel room, pushing a man to the floor and handcuffing him. The man was flown to Moscow, where a court ordered he be held in pre-trial detention. It did not say when the arrest or court hearing occurred. The charges carry up to 20 years in prison.

Japan’s foreign ministry urged Moscow to extend “fair and impartial treatment” to the detained journalist. “The Japanese embassy … in Moscow and the consulate general in Yuzhno-Sakhalinsk lodged a request with the Russian authorities for the prompt provision of information, as well as for humanitarian consideration and fair and impartial treatment,” an official told Agence France-Presse.

The Hokkaido Shimbun said in a statement that it was aware of the announcement by Russian authorities but it was “still confirming the details”.

“Ensuring the safety of the journalist is our top priority, and we are responding accordingly,” it said.

Imai’s arrest comes amid rapidly deteriorating ties between Japan and Russia, triggered by Tokyo’s support for Ukraine and a longstanding dispute over sovereignty of islands belonging to the Kuril chain near Sakhalin that are known in Japan as the Northern Territories. Japan claims the four islands closest to its territory – the nearest is less than 4km from Hokkaido.

Russia regards Japan as an “unfriendly” country because it has joined western sanctions over its war ⁠in Ukraine. Russia has arrested several citizens of “unfriendly” countries in recent years, accusing them of working for western intelligence services.

In 2023, US journalist Evan Gershkovich was arrested on espionage charges, later sentenced to 16 years in prison before being released in a 2024 prisoner swap.

The FSB said it had “opened a criminal case against the Japanese national”, and that he had been placed in pre-trial detention, Russian news agencies reported, citing the agency.

Russian media reported he would remain in custody until 12 December.

“Attempts by Tokyo to use its correspondents in Russia … to gather information aimed at undermining the security of our state is regrettable,” Zakharova said, alleging this was “not an isolated case”.

The Kurils have been under Russian control since the end of the second world war, when Soviet forces seized the islands in the final days of the conflict, forcing about 17,000 Japanese citizens to leave and, over time, replacing them with a similar number of Russians.

In 2022, Moscow scrapped a programme that allowed former residents to travel to the islands to visit the graves of their ancestors in protest at Japan’s support for Ukraine.

Russia’s president, Vladimir Putin, visited one of the disputed islands in August, causing an ​uproar in Japan. Tokyo has ‌said it would continue ​implementing sanctions against ​Russia and supporting Ukraine.

With Agence France-Presse and Reuters