Chancellor Olaf Scholz is expected to announce the appointment later on Tuesday.

It follows the resignation of Christine Lambrecht at a crucial time for the ministry, with Germany under intense pressure to send battle tanks to Ukraine.

If confirmed, Pistorius, who is a member of Scholz's Social Democrats (SPD), would be a surprise choice for the post.

He would beat much better known politicians who were thought to be in the running, such as Eva Hoegl, the parliamentary commissioner on armed forces, and Employment Minister Hubertus Heil.

It would also end a streak of having three female defence ministers, as well as upending a promise by Scholz to keep his cabinet gender-balanced when he became chancellor in 2021.

Born in Osnabrueck, Pistorius studied law and worked as a lawyer before entering politics in the 1990s.

Before taking up his post in Lower Saxony, he was the mayor of Osnabrueck.

Pistorius has gained a reputation for his work in renewing the police force in Lower Saxony and boosting it to combat extremism.

Der Spiegel noted he is "the most visible" of the state interior ministers, and is "well connected with the security authorities".

He had previously been rumoured to be in the running for the post of federal interior minister, which looks set to be vacated later this year by current postholder Nancy Faeser.

His expected appointment as defence minister would see him follow in the footsteps of other high-profile politicians who graduated to national politics from Lower Saxony, such as Sigmar Gabriel and Gerhard Schroeder.

Pistorius would have a huge task on his hands, taking up the new post days ahead of a crucial meeting of defence ministers from Ukraine's allies, at a time when Berlin is under intense pressure to provide battle tanks to Kyiv.

Lambrecht, who had come under fire over an escalating series of gaffes, handed in her resignation on Monday.