Airspace above Ukraine has become devoid of traffic after Russia launched a land, sea and air invasion of its neighbour.

Websites tracking aircraft across Europe show a large void in the skies above the country as fighting breaks out in many regions. 

Europe's aviation regulator warned about hazards to flying in bordering regions, with Moldova, southwest of Ukraine, also closing its airspace

Belarus to the north said civilian flights could no longer fly over part of its territory after Russian President Vladimir Putin authorised the military operation.

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Ukraine State Air Traffic Services Enterprise said on its website that the country's airspace was closed to civilian flights from 0045 GMT on Thursday. Air traffic services were suspended.

The European Union Aviation Safety Agency (EASA) said airspace in Russia and Belarus within 100 nautical miles of their borders with Ukraine could also pose safety risks.

"In particular, there is a risk of both intentional targeting and misidentification of civil aircraft," the agency said in a conflict zone bulletin.

"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."

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EASA said Russia's defence ministry had sent Ukraine an urgent message warning of a high risk to flight safety, due to the use of weapons and military equipment from 0045 GMT, and asked Ukraine's air traffic control to stop flights.

Before Ukraine's announcement, Britain, Canada, France, Italy and the United States told their airlines to avoid certain airspace above eastern Ukraine and Crimea but stopped short of a total ban.