Tens of thousands of Russian troops remain in and around Ukraine.

Axar.az reports citing foreign media that NATO Secretary-General Jens Stoltenberg said on Thursday.

"We have seen some reduction in the number of Russian troops, but tens of thousands remain, and we are also seeing that Russia has kept a lot of weapons ... and equipment," said Stoltenberg in a doorstep statement ahead of a meeting of the EU defence ministers in Brussels.

The NATO chief said Russia was also imposing restrictions in the Black Sea, including on access to the Sea of Azov through the Kerch Strait, adding that NATO should remain vigilant and closely monitor the developments.

"Overall, there is a significant Russian presence, and there are many more Russian troops now, in and around Ukraine than before the recent increase in tensions," he added.