Russia's air navigation service provider Rosaeronavigatsia is refusing Ukraine International Airlines permission to fly over the country on routes to Armenia, Azerbaijan, Georgia and Kazakhstan.
This affects UIA's scheduled flights from Kiev to Astana, Baku, Batumi, Tbilisi and Yerevan. The Ukrainian flag carrier operates around 40 weekly services to these cities.
It says it has had to amend flightplans for these services to detour around Russian airspace, which will result in longer flight times. For example, its flight between Kiev and Tbilisi will take a half-hour longer.
Russian media reports suggest that discussions are under way toward imposing a blanket ban on overflights of Russian airspace by Ukrainian operators.
Sources say Dniproavia – which serves Baku, Tbilisi and Yerevan from Dnepropetrovsk and Kharkov – has also come under restrictions.