The body of the fighter, identified as Tomas V., was recovered from a battlefield near the town of Kupiansk during a special operation on Tuesday night, weeks after he went missing in Ukraine.

"Volunteer Tomas was killed in action while on a combat mission with Ukraine's International Legion," the Lithuanian NGO Blue/Yellow said.

The NGO had been involved in the operation to retrieve his body, which it called "complex and dangerous".

The efforts led by Ukraine's Special Operations Forces involved special equipment to camouflage the troops, since the body was in an area under heavy shelling.

Lithuania, an EU and NATO member, has been a staunch ally of Ukraine since Russia invaded the country in February 2022.

Lithuania and its fellow Baltic states Estonia and Latvia fear that Russia could target them next.

Lithuanian President Gitanas Nauseda said in a statement that Tomas V. fought "for both Ukraine and Lithuania".

"May the heroism and dedication to the ideals of freedom of the fallen soldier remain forever in our memory," Nauseda said.

The Lithuanian foreign ministry confirmed reports of a volunteer fighter missing in Ukraine on March 19.

Tomas V. was the second Lithuanian fighting for Ukraine to die on the battlefield, after a man was killed last year.