VILNIUS, Lithuania (AP) — Two people have been detained in Poland on suspicion of attacking Russian opposition activist Leonid Volkov, an ally of the late activist Alexei Navalny, the Lithuanian president announced on Friday.

Volkov was attacked in March outside his home in the Lithuanian capital, Vilnius, where he lives in exile. The attacker smashed one of his car’s windows, sprayed tear gas into his eyes and hit him with a hammer, police said at the time.

President Gitanas Nausėda announced the arrests to reporters in Vilnius and thanked Poland for its work. He said the suspects would be handed over to Lithuania but did not specify when.

“Two people have been detained in Poland on suspicion of beating Russian opposition leader Leonid Volkov. I thank the Republic of Poland for the excellent work it has done. I have discussed this with the Polish president and thanked them for their excellent cooperation,” Nausėda said.

There was no immediately comment from Polish President Andrzej Duda or any other Polish officials.

Volkov said on X, formerly Twitter, that he didn’t know the details of the arrest, but “saw how energetically and persistently the Lithuanian police have worked over the past month on this case” and was “very glad that this work has paid off.”

“As for the details, we will find them out soon. Can’t wait to find out!” Volkov wrote.

Volkov suffered a broken arm in the brutal attack and was hospitalized. He accused Russian President Vladimir Putin’s “henchmen” of responsibility in the attack and vowed to keep up his opposition work.

The attack on Volkov took place nearly a month after Navalny’s unexplained death in a remote Arctic penal colony. He was Russia’s best-known opposition figure and Putin’s fiercest critic. Navalny had been jailed since January 2021 and was serving a 19-year prison term there on the charges of extremism widely seen as politically motivated.

Opposition figures and Western leaders laid the blame on the Kremlin for his death — something officials in Moscow vehemently rejected.

His funeral in the Russian capital on March 1 drew thousands of supporters, a rare show of defiance in Putin’s Russia amid an unabating and ruthless crackdown on dissent. Navalny’s widow, Yulia, vowed to continue her late husband’s work.

Volkov used to be in charge of Navalny’s regional offices and election campaigns. He ran for mayor of Moscow in 2013 and sought to challenge Putin in the 2018 presidential election. Volkov left Russia several years ago under pressure from the authorities.