British citizen Aiden Aslin and Moroccan Brahim Saadun, sentenced to death by a court in separatist-controlled Ukraine, submitted their appeals on Monday.
In June, Aslin, Saadun and another British citizen, Shaun Pinner, were accused of acting as mercenaries for Ukraine and sentenced to death by separatist authorities in the self-proclaimed Donetsk People's Republic.
The Supreme Court of the breakaway territory said in a statement on Monday that Saadun had filed an appeal.
Separately, a representative of the separatist statelet's court told state news agency RIA Novosti that Aslin had also lodged an appeal.
Britain has expressed fury over the death sentences handed to the two Britons in the case.
They surrendered in April in Mariupol, a port city in southern Ukraine that was captured by Russian troops after a weeks-long siege.
