Russian Foreign Minister Sergei Lavrov was forced to cancel a visit to Serbia because neighboring countries closed their airspace.

In comments reported by Russian news agencies, Foreign Ministry spokesperson Maria Zakharova called the move "another closed channel of communication."

Lavrov was scheduled to meet with Serbian President Aleksandar Vui in Belgrade on Monday, but Bulgaria, North Macedonia, and Montenegro closed their airspace to the plane carrying Moscow's top diplomat, according to the Serbian newspaper Vecernje Novosti.

Serbia and Russia have deep historical, religious, and cultural ties, with Belgrade refusing to join Western sanctions against Moscow. Vui accused Ukraine and an unidentified EU country of orchestrating a series of bomb hoax threats against Air Serbia planes in April. 

The president has also avoided joining the rest of the West in condemning Russia's actions in Ukraine.

Vui and Russian President Vladimir Putin agreed last month that Russia would continue to supply natural gas to Serbia, despite the fact that other countries have been cut off because they refuse to pay for Russian gas in rubles.