MOSCOW, April 17. /TASS/. The Russian side informed Ukraine’s Charge D’Affaires Ad Interim Vasily Pokotilo about its decision to expel Ukrainian consul in St. Petersburg Alexander Sosonyuk detained by the Federal Security Service (FSB) for obtaining law-enforcers’ classified data, Russia’s Foreign Ministry said in a statement on Saturday.

The Ukrainian diplomat must leave Russian territory by April 22, the ministry said.

"The Russian side pointed to the inadmissibility of such activity incompatible with the consular status and damaging the security interests of the Russian Federation. It stated that his stay on Russian territory was undesirable and recommended that he should leave it within 72 hours beginning from April 19," the statement says.

On April 16, the Federal Security Service apprehended a consul of the Ukrainian General Consulate in St. Petersburg upon receiving classified data from the databases of Russian law-enforcement agencies and the FSB.

As the FSB stressed, "this activity is incompatible with the status of the diplomatic employee and is of clearly hostile nature towards the Russian Federation."

Russia will apply measures to the apprehended Ukrainian diplomat in accordance with international law, the FSB press office said.

Under international law, diplomats enjoy diplomatic immunity in the countries where they work but can be deprived of the right of staying in the receiving state, if they breach law or commit hostile actions.

As follows from the Vienna Convention, the receiving state may at any time notify the sending state that the head of the mission or any member of the diplomatic staff of the mission is persona non grata and the diplomat's stay in the country is not acceptable.