CETINJE, Montenegro — Riot police used tear gas on protesters who fired gunshots in the air and hurled bottles and stones early Sunday in Montenegro before and during an inauguration of the new head of the Serbian Orthodox Church in the country.

Sunday’s ceremony held in Cetinje, a former capital of the small Balkan nation, has angered opponents of the Serbian church in Montenegro, which declared independence from neighboring Serbia in 2006.

On Saturday, hundreds of protesters confronted police in Cetinje around a monastery where the inauguration of Metropolitan Joanikije took place after he and the Serbian Patriarch Porfirie arrived with a helicopter, the state RTCG reported.

The TV station showed footage of the priests being led into the monastery by heavily armed riot police holding bulletproof vests over their bodies to protect them.

The demonstrators also set up road barriers with trash containers, tires and large rocks in an attempt to prevent church and state dignitaries from coming to the inauguration.

Chanting “This is Not Serbia!” and “This is Montenegro!,” many of the protesters spent the night at the barriers amid reports that police were sending reinforcements to break through the blockade. The protesters, some firing handguns into the air, set fire to car tires at one of the blockades, trying to prevent police from breaking through

Montenegrins remain deeply divided over their country’s ties with neighboring Serbia and the Serbian Orthodox Church, which is the nation’s dominant religious institution. Around 30% of Montenegro’s 620,000 people consider themselves Serb.

Metropolitan Joanikije said after the ceremony that “the divisions have been artificially created and we have done all in our power to help remove them, but that will take a lot of time.”

The situation flared up in Cetinje early Sunday after a relatively calm night that followed Saturday’s clashes and a parallel gathering in the capital, Podgorica, where thousands of people greeted Serbian Patriarch Porfirije and Metropolitan Joanikije before the inauguration.

In a clear demonstration of the sharp political and social divide in Montenegro, President Milo Djukanovic, the architect of the state’s independence from Serbia, visited Cetinje while the current pro-Serb Prime Minister Zdravko Krivokapic went to Podgorica.

Krivokapic branded the protests as “an attempted terrorist act,” while Djukanovic said he wasn’t taking sides as the president of all citizens while praising the protesters in Cetinje for guarding national interests against the alleged bid by Serbia to impose its influence in Montenegro through the church.

Djukanovic has urged that the inauguration be postponed and some media late Saturday reported this would happen, but the information was soon denied by the Serbian church which said the inauguration would take place despite the tensions.

Serbian President Aleksandar Vucic, who has been accused by the opposition in Montenegro of meddling in its internal affairs in conjunction with Russia, congratulated Joanikije on his inauguration and praised the government for going ahead with the ceremony despite the clashes.

Vucic told the pro-government TV Prva in Belgrade that Serbia has no “aspirations” toward Montenegro “but only the closest and best relations.”

Since Montenegro split from Serbia, pro-independence Montenegrins have advocated for a recognized Orthodox Christian church that is separate from the Serbian one.

The U.S. government urged all sides “to urgently de-escalate the situation,” according to a U.S. Embassy statement.

“Religious freedom and the freedom of expression, including to peacefully assemble, must be respected,” it said.

“We urge citizens not to take their anger out on the police as they try to uphold public order and to police to use only the means necessary to restore peace,” the statement said.

Joanikije’s predecessor as the church’s leader in Montenegro, Amfilohije, died in October after contracting COVID-19.

The Serbian Orthodox Church played a key role in demonstrations last year that helped topple a long-ruling pro-Western government in Montenegro. The new government now includes staunchly pro-Serb and pro-Russian parties.

Montenegro’s previous authorities led the country to independence from Serbia and defied Russia to join NATO in 2017. Montenegro also is seeking to become a European Union member.

Dusan Stojanovic and Jovana Gec contributed to this report from Belgrade, Serbia.