April 17 (UPI) -- Russia and Ukraine expelled each others' diplomats Saturday amid escalating tensions between the two countries.
Moscow informed Ukrainian diplomatic officials of its decision to expel Ukrainian consul in St. Petersburg Alexander Sosonyuk by next Thursday, Russia's Foreign Ministry said in a statement to TASS Saturday.
The Federal Security Service detained Sosonyuk Friday, accusing him of obtaining classified information from Russian law enforcement agencies -- an activity the FSB emphasized was of a "clearly hostile nature towards the Russian Federation," according to TASS.
Sosonyuk has been ordered to leave Russia within 72 hours, with the countdown starting Monday.
Ukraine's Ministry of Foreign Affairs denied the accusations against Sosonyuk in a statement condemning Russia for his detention, and responded in kind by expelling a senior diplomat of the Russian embassy in Kyiv.
"We strongly protest against the April 16 illegal detention of a staff member of the Consulate General of Ukraine in Saint Petersburg and the order for him to leave the territory of the Russian Federation until April 21," the statement said. "We absolutely reject the accusations made against the consular officer."
Russia's senior diplomat has been ordered to leave within 72 hours, starting Monday, Ukraine's foreign affairs ministry said in the statement.
Kyiv said Sosonyuk's expulsion "grossly violate(s) the Vienna Convention on Diplomatic Relations of 1961 and the Vienna Convention on Consular Relations of 1963 and confirm Russia's choosing the line of hostility with Ukraine."
"The President voiced our concerns over the sudden Russia military build-up in occupied Crimea and on Ukraine's borders, and called on Russia to de-escalate tensions," a readout of the call said.