Russia will begin calling up tens of thousands of soldiers next week in a conscription drive to replenish its armed forces and build up its military reserves.

Moscow says conscripts are not sent to fight in Ukraine but the draft -- which happens twice a year -- comes amid persistent rumours of a new wave of mobilisation for the Ukraine offensive.

"The spring draft will be held from April 1," deputy head of the defence ministry's mobilisation department, Rear Admiral Vladimir Tsimlyansky, said in a briefing on Friday.

"Conscripts will not be sent to the armed forces' deployment points in the new regions of Russia -- the Donetsk and Lugansk People's Republics, Kherson and Zaporozhzhia regions -- or (be sent) to perform tasks of the special military operation," he added, using Russia's official language for its offensive against Ukraine.

Moscow unilaterally annexed the four Ukrainian regions in 2022 and has pressurised their residents to take Russian citizenship.

Some 147,000 conscripts were drafted during last year's spring call-ups. The army did not say how many it was targeting this year.

Russian men aged between 18 and 30 are eligible to be called up after lawmakers increased the upper age limit from 27 last year.

Military service lasts 12 months.

Conscripts face intense pressure once in the armed forces to sign voluntary military contracts which allow them to be sent to fight in Ukraine.

  Fresh concerns 

 Russia says it recruited more than 400,000 for its campaign last year, with the defence ministry offering high salaries for fighters.

It has been accused of focussing recruitment on Russia's poorest regions and ethnic republics.

Once conscripts have completed military service, they form part of Russia's military reserves and are liable to be sent to the front lines if mobilised in the future.

Mobilisation rumours have persisted since the Kremlin forcibly drafted more than 300,000 in autumn 2022.

Putin said in December there was "no need" for another wave, pointing to successful recruitment efforts.

But his re-election victory earlier this month -- combined with the defence ministry saying it would create two new armies by the end of the year and the Kremlin pointing at Ukraine for last week's deadly attack on a Moscow concert hall -- have all triggered fresh concerns.

"By voting for Putin, you voted for mobilisation," Abbas Gallyamov, a former speechwriter for the Russian leader and now an anti-Kremlin campaigner, said on Telegram last week.

The team of late Kremlin critic Alexei Navalny on Thursday urged people who are issued military summons to ignore them and not report to draft offices.

Putin said in December that 617,000 Russian servicemen were deployed in the "conflict zone".

He issued a decree last year that ordered the overall size of the army to be increased to 1.32 million troops, from its previous level of 1.15 million.