Belarus is lashing out at Moscow after Russia said it had established a security zone on the border between the closely linked neighbors.
In remarks published on February 2, Belarusian Foreign Ministry spokeswoman Maria Vanshyna said the Russian move "contradicts a large number of bilateral agreements on the basic principle of transparency of the border between Belarus and Russia."
It came a day after the Russian Federal Security Service (FSB) said that a "full-fledged border-protection regime" was established following Belarus's announcement last month that it was abolishing visas for short-term visitors from some 80 countries, including the United States and European Union members.
Moscow has said that the new visa policy, which takes effect on February 9, poses a security threat to Russia.
In her comments to news site Tut.by that were also published on the ministry's website, Vanshyna said that Russia's decision was unilateral and had not been coordinated with Belarus.
Russia and Belarus established what they call a "union state" in the 1990s, and there have been no border controls. The two countries have closer ties than any other former Soviet republics, but Belarus has hinted at concern over Russia's interference in neighboring Ukraine and Moscow bristles at Belarusian President Alyaksandr Lukashenka's efforts to court the West.