BRUSSELS

NATO’s military leaders will re-establish contact with their Russian counterparts amid fighting in eastern Ukraine between Ukrainian troops and pro-Russian rebels, according to NATO’s top military commander.

NATO's top military commander General Philip Breedlove told a news conference at the alliance's headquarters in Brussels on Thursday: "We have talked an awful lot about how we re-establish [communication] and the fact that the communication with our senior military interlocutors in Russia is important." 

Breedlove disclosed he had continued to be in contact with Valery Gerasimov, chief of the general staff of Russia's armed forces, after Russian troops entered Crimea in 2014.

''We have talked among several of us senior military leaders how we will do that … but yes, we are going to re-establish communication with Valery [Gerasimov],'' Breedlove said.

Breedlove’s comments came amid fierce fighting at Donetsk airport in eastern Ukraine between Ukrainian troops and pro-Russian militants, in which six soldiers were killed and 16 injured, according to the Ukrainian government.

- 'Russian pressure'

Breedlove also said NATO had detected signs of stronger Russian involvement in the fighting in eastern Ukraine. 

While he said he could not confirm the exact estimated number of Russian troops in Ukraine, Breedlove said: "... Russian-backed forces have renewed capability now to bring pressure on the Ukrainian forces and have in several places moved the line of contact to the west and this is concerning."

Ukraine's President Petro Poroshenko claimed at the World Economic Forum in the Swiss resort of Davos on Wednesday that Russia had more than 9,000 soldiers in eastern Ukraine. 

NATO member states have accused Russia of providing pro-Russian rebels in eastern Ukraine with tanks, advanced air defense systems and other heavy weapons – allegations that Russia denies.