A Russian man has been charged in Poland over a hammer attack in neighbouring Lithuania on a top aide of late Russian opposition leader Alexei Navalny earlier this year, prosecutors said on Friday.
"Last week, charges were brought against a Russian national suspected of organising the beating" of Leonid Volkov on March 12, the prosecutor's office said in a statement.
The statement only named the man as Anatoly B, saying he had been detained on September 13 in Poland.
He is accused of being behind the attack, motivated by Volkov's "political activity", it said.
Prosecutors said they were investigating a total of eight people in the case -- six Poles, a Belarusian and the Russian who has been charged.
Volkov was briefly admitted to hospital after having been repeatedly struck with a hammer outside his home in Lithuania's capital Vilnius.
The attack has led to a bitter war of words between two leading anti-Kremlin Russian opposition factions.
The Navalny-founded Anti-Corruption Foundation (FBK) last week posted a video accusing Leonid Nevzlin, a former executive at ex-oil tycoon Mikhail Khodorkovsky's now-defunct oil company, of ordering the attack.
Volkov himself made a similar allegation in a post on social media channels.
"Leonid Nevzlin was ready to pay $250,000 to perpetrators who were supposed to make me disabled and hand me over to the FSB" Russian security service," he wrote.
Nevzlin's denial
Nevzlin, writing on Telegram, has rejected the allegations. The legal authorities would confirm their "absurdity" and "complete groundlessness", he said.
He accused the FBK of getting its information from inside Russia.
The foundation's recent work, he said, was "completely within the framework of the Kremlin's information policy and... the tasks set by the Russian special services".
Khodorkovsky, based in London since his 2013 release from more than a decade in jail in Russia, defended Israel-based Nevzlin on his social media channels.
He described him as "my long-term business partner, comrade and friend".
The former oil magnate also noted that state-run Russian channel RT had published similar allegations against Nevzlin in a report that was barely noticed at the time.
The FBK has rejected any suggestion of collusion with RT.
Of the accusations, Khodorkovsky said: "Either this is true and then Leonid Nevzlin has gone crazy. Or this is an FSB provocation and a fake, on which a lot of money was spent.
"I am inclined to choose the second version," he added.
Analysts say the Russian opposition is in urgent need of a new unifying figure after the death of Navalny.
Supporters say he was killed on the orders of the Kremlin, although this is denied by Moscow.