Hungary's supreme court has rejected the appeals of three men sentenced to life in prison for a series of attacks against Roma in which six people were killed and several injured.

Zsolt Peto and brothers Arpad and Istvan Kiss were found to have carried out nine attacks, mostly on the outskirts of rural villages, against Roma, also known as Gypsies. Their sentences exclude the possibility of parole.

One of the victims was a 5-year-old boy, Robika Csorba, shot to death along with his father outside their home.

Tuesday's decision by the supreme court means the appeals process has been exhausted for the three men. Their driver in some of the attacks, Istvan Csontos, is already serving a 13-year prison sentence.