Russian Foreign Minister Sergei Lavrov on Monday said at a press conference that EU countries and NATO "deprived Belgrade of the right to pursue a sovereign policy" by refusing to let his plane fly to Serbia, Sputnik news agency reported.

"The unthinkable has happened," Lavrov said.

He also said that Russia would respond to Western deliveries of long-range weapons to Ukraine by pushing back Ukrainian forces further from Russia's border.

The Kremlin denounced the "hostile" actions of several European countries. "Such hostile actions against our country can cause certain problems," Kremlin spokesman Dmitry Peskov said while insisting that Russia and Serbia would continue contacts.

(With input from agencies)