"That's a lot of money," Scholz told news site Focus online, adding: "We have a very clear procedure in NATO" on decision-making, with alliance members currently asked to spend two percent of GDP on defence.

The centre-left leader said that five percent of GDP would amount to about 200 billion euros ($206 billion) a year.

That compares to a federal budget of about 490 billion euros, Scholz said, meaning that Germany would have to find an additional 150 billion euros a year.

"And that's why I think it's better to concentrate on the path that NATO has long agreed on," he said.

Scholz conceded, however, that "Germany must do more for security," stressing that Berlin had already roughly doubled annual defence spending to almost 80 billion euros over recent years.

After Russia's full-scale invasion of Ukraine in 2022, Scholz had also announced an additional one-off sum of 100 billion euros to upgrade Germany's armed forces.

Speaking at a meeting on Ukraine at the Ramstein airbase in southern Germany, Defence Minister Boris Pistorius also said five percent of GDP was too much, pointing out that it would amount to "around 40 percent" of the entire federal budget for Germany.

"I don't know which country will be able to afford that," he said, adding that what counts is "not a question of percentages" but rather how NATO's capability goals "are defined and met".