PRAGUE (Reuters) - Slovak Prime Minister Igor Matovic apologised on Thursday after jokingly suggesting that Russia take a part of western Ukraine as payment for delivering doses of its Sputnik V vaccine to Slovakia. Matovic bypassed his cabinet partners to order the Russian vaccine even though it has not yet been approved for use in the European Union, of which Slovakia is a member. Asked in a radio interview what he had promised Russia in exchange for the vaccine, Matovic jokingly said he had offered “Transcarpathian Ukraine”, referring to the western Ukrainian region bordering Slovakia. Jokes about territorial integrity are an especially sensitive issue for Ukraine, after Russia annexed its Crimea peninsula in 2014 and has backed armed separatists battling Kyiv’s forces in eastern Ukraine. Russia’s actions triggered EU and U.S. sanctions against Moscow. Matovic said on Twitter on Thursday that Slovakia’s position on respecting Ukraine’s territorial integrity and maintaining international law was clear. “I apologise to all Ukrainians for my inappropriate reaction, which could undermine their just efforts,” he said, without elaborating. Ukraine’s Foreign Minister Dmytro Kuleba said Ukraine would have taken further steps had Slovakia not apologised. “No one will ever have the right to insult Ukraine with any word or hint that questions its territorial integrity or tries to demonstrate that the fate of Ukraine is being decided somewhere other than Ukraine,” Kuleba told reporters in Kyiv. “And in this regard, for all our friendship with our Slovak colleagues, our reaction to such actions will not only be tough, but extremely tough.”