A senior diplomat at the Russian Embassy to Ukraine must leave the country in response to an incident involving the Ukrainian consul in St. Petersburg, the Ukrainian Ministry of Foreign Affairs said on Saturday.

"A senior diplomat of the Russian embassy in Kyiv must leave Ukraine within 72 hours, beginning from April 19," the ministry said.

The arrest of the Ukrainian diplomat in St. Petersburg was unlawful, such actions violate the 1961 Vienna Convention on Diplomatic Relations and the 1963 Vienna Convention on Consular Relations, the ministry said. Earlier the ministry denied the diplomat's involvement in obtaining secret information.

This morning the FSB said that Sosoniuk had been caught red-handed while trying "to obtain classified information from the databases of the Russian law enforcement agencies and the FSB. These activities are incompatible with the status of a diplomatic worker and are clearly hostile towards the Russian Federation. Measures in accordance with international law will be taken against the foreign diplomat."

Later the Russian Foreign Ministry said that Sosoniuk must leave Russia within 72 hours.