Kosovo's Parliament has failed to pass constitutional amendments that would allow the establishment of a special court to prosecute war crimes including the killing of hundreds of Serb civilians.

In a major blow to relations between Kosovo and its main international backer, the United States, the 120-seat legislature voted 75-7 on Friday in favor of the amendments. A two-thirds majority of 80 votes was needed to approve the changes.

A European Union investigation probed alleged crimes committed during Kosovo's war for independence from Serbia, but the special court must be established to issue indictments.

A 2010 Council of Europe report claimed former rebel leader turned politician Hashim Thaci and other Kosovo guerrillas ran a criminal ring in 1999 that targeted Serbs, Romas and also ethnic Albanians.