Under the plan, all 18-year-old men will from next year have to fill in a questionnaire on whether they would want to serve and undergo an armed forces physical test.

No one will be compelled to join the Bundeswehr, however, said Defence Minister Boris Pistorius. He has advocated instead a campaign to make military service more attractive to draw more male and female recruits.

Chancellor Friedrich Merz has made bolstering Germany's ill-equipped military a major priority, citing a hostile Russia and doubts about future US security commitment to Europe.

He has moved to sharply increase spending on the military and vowed to turn the Bundeswehr into "the strongest conventional army in Europe".

The cabinet approved a revamped military service model in August, spearheaded by Pistorius of the centre-left SPD.

But members of Merz's conservative CDU/CSU then called for a compulsory element in the form of a "draft lottery", to be applied if there were not enough volunteers.

The lottery idea has been scrapped for now, part of a deal reached late Wednesday, said Jens Spahn, leader of the CDU/CSU parliamentary faction.

"If voluntary service is ultimately not enough, then compulsory service will also be necessary," Spahn said, adding however that that would require further legislation.

Matthias Miersch, the SPD's parliamentary group leader, said he was certain the Bundeswehr could find enough volunteers, calling the new model "an offer" to young men and women, "not an obligation".

Pistorius said compulsory service would be a "last resort" and the focus would be on "designing an attractive service".

"I am very confident that all this will succeed," he added.

"Other European countries, especially in the north, show that the principle of voluntary service combined with attractiveness works, and I expect the same here."