Montenegro and Serbia on Saturday expelled one another's ambassadors in an escalating diplomatic spat.
The tit for tat began when Montenegro declared the ambassador of Serbia a persona non grata and expelled him from the country.
Vladimir Bozovic had interfered with domestic issues and so broke the country's laws, according to the Foreign Ministry in Podgorica.
Serbia responded a few hours later, declaring the Montenegrin ambassador Tarzan Milosevic persona non grata and expelling him from the country.
The government in Montenegro is expected to remain in place only for the next four days, as a new coalition prepares to replace it following elections during the summer.
Montenegrin President Milo Djukanovic has headed the country for nearly 30 years without interruption, leading the country to independence from Serbia in 2006 and into NATO in 2017.
During his rule he steered Montenegro away from its traditional alliance with Serbia and Russia to join NATO in 2017.
However, Djukanovic's Democratic Party of Socialists (DPS) lost in parliamentary elections in August.
On Wednesday, Montenegro's parliament is due to vote on a new government that unites three opposition groups.
The most powerful party is the pro-Russian, pro-Serbian Democratic Front (DF). Its partners, however, insist that Montenegro must remain on its pro-Western course.
