A United Nations war crimes court has upheld the convictions of two Bosnian Serbs accused of killing more than 100 people during the Balkans conflict of the 1990s.

The appeals court on Tuesday affirmed the life sentence of Milan Lukic, a founding member of a group known as the White Eagles, or the Avengers, which worked with police and military units to murder, torture and terrorize Muslim communities.

Judges upheld Lukic's 2009 conviction for crimes, including the burning deaths of more than 100 Muslims locked in buildings by his paramilitary forces.

His cousin, Sredoje Lukic, was found guilty of aiding in the crimes. But the same court reduced his 30-year sentence to 27 years after acquitting him on charges of beating prisoners.

Both men were accused of crimes against humanity and war crimes for atrocities committed in the eastern Bosnian town of Visegrad in 1992 and 1993.