Montenegro and Serbia have expelled each other’s ambassadors over a historical dispute dating back more than a century.
Serbian ambassador to Montenegro, Vladimir Bozovic, described a decision by Montenegrin authorities in 1918 to unify with Serbia as a “liberation”.
He was accused of “interfering in Montenegro’s internal affairs” and given 72 hours to leave the country.
Montenegro’s ambassador to Serbia, Tarzan Milosevic, was also expelled.
The 1918 assembly ruled that Montenegro would become part of the Kingdom of Serbs, Croats and Slovenes, which was later known as Yugoslavia. In 2006, Montenegro declared independence, becoming a sovereign state for the first time since the end of the First World War.
Mr Bozovic made the comments at a meeting of an association representing Montenegrin Serbs. He described the decision in 1918 as a “free expression of people’s will to unite with fraternal Serbia”.
Montenegro’s foreign ministry said Mr Bozovic had “belittled the state which gave him a diplomatic immunity”.
It added that he had been given several verbal and written warnings.
In retaliation, Mr Milosevic was asked to leave Serbia.
The outgoing Montenegrin government, which decided on the expulsion of Mr Bozovic, is set to be succeeded by a new pro-Serb cabinet of parties which narrowly won the election in August. The new government is set to be voted into office next week.