Volkov, ally of the late Kremlin critic Alexei Navalny, lives in Lithuania and was attacked near his home in March.
“Two people were detained in Poland on suspicion of beating Russian opposition leader Leonid Volkov,” Nausėda said on Friday.
“I thank Poland for a truly excellent job. I spoke with Polish President Andrzej Duda about this and thanked him for the excellent cooperation. I would also like to thank our criminal intelligence officers, who did that first and most important preparatory work,” the president said.
The suspects will be handed over to Lithuania after the necessary procedures are completed, the president said, adding he could not comment on further details.
Volkov was attacked and injured while sitting in a car outside his house in Vilnius on 12 March. The attacker broke a car window, sprayed tear gas and started hitting him with a hammer.
Volkov, 44, was taken to hospital for medical aid but was later discharged.
A pre-trial investigation over non-severe health impairment was launched, a crime punishable by restriction of liberty or by arrest or by a custodial sentence for a term of up to three years.
Volkov was a colleague of Navalny, who died in a Russian prison in February. Volkov left Russia due to a threat of arrest and currently resides in Lithuania.