According to analyst Ukraine Weapons Tracker, Ukrainian defenders received FN F2000 assault rifles. Belgium handed them over to Ukraine as military aid. According to Ukraine Weapons Tracker, the first batch included 10,000 assault rifles, including FN SCAR and FNC.
If you suddenly did not know
The FN F2000 is a Belgian assault rifle developed by Fabrique Nationale de Herstal. It was first introduced in 2001. This weapon is designed to perform combat missions in modern local military conflicts. The machine is made of polymer. By the way, FN F2000 can be found in many computer games, including S.T.A.L.K.E.R, Call of Duty: Modern Warfare 2, Warface, etc.
For those who want to know more