Polish police detain two men suspected of attacking Navalny's aide Leonid Volkov

Volkov suffered injuries from hammer blows in the attack on March 12 outside his home in Vilnius, the Lithuanian capital.

Lithuanian counterintelligence said at the time that the attack was the work of Russian special services. The Kremlin declined to comment.

Polish police said on the social media platform X that they had arrested the two suspects in cooperation with Lithuanian police in response to a European arrest warrant.

A spokesperson for the court in Warsaw that is dealing with the case said the suspects were accused of "acting in an organised group, executing the orders of the special services of a foreign country" and of damaging the health of a Russian citizen in Lithuania.

The spokesperson said the suspects would be held in pre-trial detention for 40 days and that their lawyers had lodged an appeal.

Polish Prime Minister Donald Tusk said on X that Poland had also detained a Belarusian citizen working for Russia who was suspected of ordering the attack, and that the attackers themselves were linked to football hooliganism.

The Belarusian foreign ministry did not immediately reply to an emailed request for comment.

In Vilnius, the deputy head of Lithuania's criminal police, Saulius Briginas, told a press conference that the suspects were both Polish citizens and had been detained on April 3 in Warsaw.

The two suspects have been charged in Lithuania with intentionally causing minor bodily harm to Volkov because of his beliefs, which is punishable by a fine or a jail term, chief Vilnius prosecutor Justas Laucius said.

"At this time, the charge is that the crime was committed due to (Volkov's) beliefs and his political activities", Laucius told the same news conference in Vilnius.

The suspects could be extradited to Lithuania by May, Laucius added.

The two suspects were previously known to Polish police and had travelled to Lithuania to carry out the assault, said Briginas.

Laucius said he did not know whether the detainees were connected to a Polish citizen who was arrested on Thursday on suspicion of planning to cooperate with Russian foreign intelligence services for a possible assassination attempt on Ukraine's President Volodymyr Zelenskiy.

Volkov himself has blamed Russian President Vladimir Putin for the attack. Before the assault he had told Reuters that leaders of Navalny's movement in exile feared for their lives.

On Friday, Volkov thanked Lithuanian police for working "energetically and persistently" on the case.

"I am very glad that this work has been effective", he said on X. "Well, we'll find out the details soon. Can't wait to find out!"

Navalny, Putin's most prominent critic, died in February in an Arctic prison. Russian authorities say he died of natural causes. His followers believe he was killed by the authorities, which the Kremlin denies.