The Higher Court in Montenegro on Thursday sentenced 13 people, including two Russian military intelligence officers and two opposition leaders, to up to 15 years in prison for staging an attempted coup in 2016.
They were found guilty of plotting to commit "terrorist acts" and undermine the constitutional order of Montenegro during the parliamentary elections in October 2016.
Montenegro's main opposition alliance, the Democratic Front, accused the court and prosecution in Podgorica of negligence, alleging that Sasa Sindjelic had been allowed to abscond so he can avoid serving a 21-year jail sentence in Croatia.
The Democratic Front claimed on Monday that Sindjelic has left the country and is reportedly in Serbia.
A former top general in Serbia's elite Gendarmerie unit, Bratislav Dikic, on Wednesday denied having backed an alleged coup plot in Montenegro during the elections in the republic last October.
Dikic told the court in Podgorica at the pre-trial session that he was a victim of the "fabricated charges" of the Montenegrin Special Prosecution.