Ukrainian forces have withdrawn from the airport of the eastern city of Luhansk following clashes with pro-Russian rebels, military officials say.

The announcement came after the two sides were engaged in all-night fighting, BBC reported.

Russian Foreign Minister Sergei Lavrov has urged negotiators meeting in the Belarus capital, Minsk, to make an "immediate ceasefire" their priority.

Some 2,600 people have died in eastern Ukraine since fighting began in April.

The conflict broke out after Russia's annexation of Ukraine's southern Crimea peninsula in March.

The rebels have been gaining ground on Ukrainian forces in recent days, in both the Luhansk and Donetsk regions, and further south around the port of Mariupol.

Bakudaily.Az