The move came as relations between Fico and President Volodymyr Zelensky have become increasingly tense over this month.In his recent remarks on Jan. 28, the Slovak prime minister called Zelensky "the enemy" of Slovakia."Many in Europe... have chosen to preserve their independence and sovereignty. But not Mr. Fico. He chooses Moscow over America and other partners who can supply his country with gas on commercial terms. This is his mistake," Ukraine's president said in response.According to the ministry's statement, the Slovak ministry delivered the Ukrainian ambassador "a strong protest" against statements by the Ukrainian side, without specifying which ones.  "(These statements) are considered interference in the internal affairs of the Slovak Republic," the ministry said. Ukraine's Foreign Ministry is yet to comment on this move.