Ukraine has closed its airspace to civilian flights after Russia began military action in the country’s east.
It cited a high risk to flight safety due to the use of weapons and military equipment in the Donbas region.
The European Union Aviation Safety Agency warned of additional safety risks in flying in bordering airspace in Russia and Belarus.
“There is a risk of both intentional targeting and misidentification of civil aircraft,” the regulator said.
“The presence and possible use of a wide range of ground and airborne warfare systems poses a high risk for civil flights operating at all altitudes and flight levels.”
Aircraft flying to or from UK airports have been ordered to avoid Ukraine’s airspace by the Transport Secretary Grant Shapps.
British citizens were advised to leave the country on Tuesday.