Russia said on Monday it had expelled a Japanese journalist for trying to obtain secret information related to Russian military capabilities in the Russian Far East, the RIA news agency reported.
The journalist, whom it didn't name, was given 72 hours to leave Russia and had already left after being detained by police in the Russian Pacific port city of Vladivostok last month, the Russian Foreign Ministry was quoted as saying.
The ministry summoned a Japanese embassy official to make an official diplomatic protest over the incident, RIA reported.
Ties between Japan and Russia are strained by a long-standing territorial row over a chain of islands in the Pacific. Known in Russia as the Southern Kuriles and in Japan as the Northern Territories, the islands were seized by the Soviet army in the waning days of World War Two.
The dispute has prevented Russia and Japan from signing a formal peace treaty to this day.
"The Japanese citizen was detained by Russian law enforcement officers in Vladivostok on Dec. 25, 2019 trying to receive secret materials about Russia's military potential in the Far East," the ministry was quoted as saying.
The announcement came two days after a Japanese telecommunications firm, SoftBank Group Corp, said one of its former employees had been arrested on suspicion of leaking company information.
The former employee is suspected of passing information to Russia's trade mission in Japan in exchange for money, the Nikkei newspaper reported, citing the police.