Montenegro police used teargas against rock-throwing demonstrators during Sunday’s coronation of a Serbian Orthodox Church cleric as the nation’s religious leader, with dozens reported wounded.

The enthronement of Joanikije II at a monastery in the town of Cetinje has stirred divisions within Montenegro over ties with neighbouring Serbia. Montenegro left its union with Serbia in 2006, but its church remained under the Serbian church.

Police used gas to separate hundreds of protesters, some of whom threw rocks, bottles and firecrackers as church figures arrived by helicopter. Some people burned tires and sat on roads.

Montenegro’s deputy police director Dragan Gorovic told state TV that 20 officers were hurt, while a state clinic in Cetinje said around 30 civilians sought help for injuries.

Prime Minister Zdravko Krivokapic described attacks on the police as terrorism. He blamed President Milo Djukanovic’s Democratic Party of Socialists, which ruled for three decades before losing elections last year, for organising protests.

Djukanovic, who opposes the enthronement, accused police of excessive force. “Today we witnessed the embarrassment of both the Church and the government,” Djukanovic said on TV.

The embassies of Germany, Italy, France, Britain, the United States and the European Union condemned violence around the enthronement of Joanikije II, who is known as the Metropolitan of Montenegro and Archbishop of Cetinje.

Djukanovic’s adviser Veselin Veljovic was arrested for participating in an attack against police on Sunday, state TV reported.