Russia has banned all dairy supplies from Ukraine, with Russia's Veterinary and Phytosanitary Surveillance Service (VPSS) citing a lack of quality control, in the latest sign of worsening trade relations between the two countries.

Ukraine signed a free-trade pact with the European Union in June and Russia, which has previously wielded import bans as punishment for countries attempting to move out of Moscow's orbit, said it was likely to respond with trade barriers.

The ban, which comes into affect on July 28, is a result of phytosanitary violations and the falsification of quality controls, said VPSS spokesman Alexei Alekseenko.

Dairy products account for only a small fraction of Ukraine's sales to Russia, but all Ukrainian exporters will be anxiously eyeing the Kremlin's trade stance because Russia accounts for nearly a quarter of Ukrainian external trade, contributing about 8 percent of gross domestic product.

Cheese represents for 0.5 percent of Ukraine's total exports and is the country's tenth-largest export to Russia, according to Nomura analysts.

(Reporting by Polina Devitt; Writing by Alessandra Prentice; Editing by David Goodman)