Blogger Mikhail Zvinchuk, founder of Rybar, a military blog on Telegram with more than 1.5 million followers, was arrested along with his wife and three others in the Montenegrin coastal town of Risan.
Zvinchuk, 35, is a former soldier and former press officer for the Russian Defense Ministry. He has been sanctioned by the EU, which accuses him of spreading disinformation and pro-Russian propaganda about the war in Ukraine.
The US has sought him on suspicion of election interference and has offered a reward of up to $10 million for information about Zvinchuk and several other Rybar associates.
Rybar confirmed the arrests and said the group was in Montenegro to film a monastery.
