A German court has upheld the convictions of a former top spy in Yugoslavia's secret service and his one-time subordinate in the 1983 killing of a dissident near Munich.

The Federal Court of Justice said Wednesday it threw out appeals by Zdravko Mustac and former subordinate Josip Perkovic, who sought to have the Munich state court's 2016 verdict overturned on procedural grounds.

The men were convicted of complicity in the murder of Stjepan Djurekovic and sentenced to life in prison. The dissident was shot and beaten in a garage in Wolfratshausen, near Munich.

The Munich court found that Mustac, the SDS agency's political head at the time, ordered Perkovic in late 1982 or early 1983 to plan and prepare the killing. The killers have never been identified.