The move comes as both Ukraine and Russia seek to gain ground and replenish their ranks in the conflict, whose front lines have barely moved in recent months.

"The increase in the full-time strength of the army is due to growing threats to our country linked with the special military operation and the continuing expansion of NATO," the army said.

It said the number of serving army soldiers would increase by some 170,000 people, and that this was an "adequate" response to the "aggressive activity of the NATO bloc".

It added that it did not plan changes to conscription or another mobilisation drive -- an unpopular measure that caused an exodus of men out of Russia last year.

Instead, the army has in recent months turned to recruitment drives, promising attractive financial rewards, especially in far-flung regions.

But Kremlin critics say this amounts to a "hidden" mobilisation, and that men have continued to be sporadically drafted into the army.