The Nordic country's Deputy Prosecutor General Jukka Rappe filed the charges against Vojislav Torden -- a commander of the Russian neo-Nazi paramilitary Rusich group -- with the Helsinki District Court on Thursday.

Torden is suspected of committing five war crimes in Ukraine in 2014, resulting in the deaths of 22 Ukrainian soldiers, and of seriously wounding four others, Rappe told AFP.

"In three of the cases Ukrainian soldiers were killed or wounded and the two other charges are about some other kind of breach of the laws of war," the prosecutor said.

In a statement, Finland's National Prosecution Authority said the charges also related to actions "contrary to the laws of war... and the treatment of wounded and killed enemy soldiers".

The suspect, who was detained at Helsinki's airport in July 2023, has denied the crimes.

Finland's supreme court has ruled that Torden, formerly known as Yan Petrovsky, could not be extradited to Ukraine due to the risk of him suffering inhumane conditions in prison there.

Earlier in October Finland's National Bureau of Investigation (NBI) completed a comprehensive probe launched in December 2023, suspecting Torden of several war crimes in autumn 2014 in eastern Ukraine.

The investigation involved close cooperation with Ukrainian prosecutors and security services as well as Europol, the International Criminal Court and Eurojust -- the European Union Agency for Criminal Justice Cooperation.

Finland has adopted "universal jurisdiction", a legal principal allowing it to bring charges on its soil for suspected crimes committed anywhere in the world.

A date for the trial has yet to be set by the court but Rappe said he expected it to begin in November.