The issue of military recruitment is particularly sensitive in Ukraine.

It affects conscripts whose military service was due to end before February 24, 2022 but was prolonged due to Russia's invasion, according to a decree by the presidency.

February 24, 2022 was the date that Russian troops crossed the border and martial law was established in Ukraine.

Authorities did not reveal how many conscripts were affected.

Zelensky said during his daily address to the nation that it would take "a few weeks" for the process to be completed but that conscripts would be demobilised "from April".

Those concerned would join the ranks of reservists but could also opt to remain in the army.

"I know that some of them have already signed a contract to serve in the armed forces," said Zelensky, without revealing how many people that was.

The question of military recruitment to replace soldiers that are exhausted after two years of war has become a thorny issue politically and socially.

Despite the need to refresh frontline troops, Kyiv is struggling to find volunteers.

It comes at a time with the army running short of ammunition and under pressure from advancing Russian troops right along the front line.

Last month, the Ukrainian parliament voted on a first reading of a bill to facilitate enlistment, which would allow the country to replace soldiers who are physically and psychologically exhausted.

But it sparked a lively debate.

The text, which could yet be changed, proposes lowering the mobilisation age from 27 to 25 and to limit military service in wartime to 36 months.

Many ordinary Ukrainians are worried about conscription, with videos circulating on social media that show the heavy-handed enlistment of young men, while information has also spread about the whereabouts of police officers distributing summonses in public spaces.