Ukraine authorities said that one of the leaders of the radical movement Right Sector died after an exchange of gunfire with police in the city of Rivne, in the West of the country.
According to reports, Oleksandr Muzychko, better known as Sashko Bily, opened fire on the officers when they tried to arrest him.
Muzychko, who led the extreme right group in Western Ukraine, was suspected of having ties to organized crime.
Three other suspects were arrested during the operation.
Russia issued an international arrest against Muzychko, for his alleged performance alongside Islamic Islamic extremists in Chechnya.