Ukrainian Prime Minister Arseniy Yatsenyuk says his country has imposed a ban on transit flights over Ukraine for all Russian airlines.
Speaking at a cabinet session in Kyiv on November 25, Yatsenyuk asked the Infrastructure Ministry to officially notify Russia about "the closure of [Ukrainian] airspace to all Russian airlines without exception."
Last month, the two countries banned landings by each other's airlines.
Yatsenyuk also said his government had decided to order Ukraine's Naftohaz oil and gas giant to stop buying natural gas from Russia.
Yatsenyuk cited as the major reason for the decision the difference between European and Russian gas prices, with European ones being "much better."
Russia's state-controlled natural-gas giant Gazprom said earlier on November 25 that it had stopped deliveries of gas to Ukraine because of Kyiv's alleged failure to make the required prepayments.