The Aidar Battalion and the Ukrainian army have so far not commented on the allegations, but his relatives confirmed to Swedish television that he had visited Ukraine sporadically and fought there.
“The Ministry for Foreign Affairs and the Embassy in Moscow are investigating these reports,” the Swedish Foreign Ministry said in comments.
The Armed Forces of Ukraine did not respond to a request for comment by the time of publication.
In the meantime, the Swedish embassy in Moscow advised its citizens against visiting Russia as “a sharp deterioration in the security situation may limit the Embassy’s ability to provide consular support.”
Earlier this week, the FSB detained a correspondent for Japan’s Hokkaido Shimbun in Sakhalin on suspicion of espionage, accusing him of gathering information about Russia’s defense capabilities.
Japanese Prime Minister Sanae Takaichi rejected Russia’s allegations. “There is no such fact,” she told reporters.