Germany's Greens-run economy ministry wants to veto Cosco's bid to buy a stake in one of the three terminals in Germany's most important port, while the Social Democrat (SPD)-run chancellery is more in favour, according to government sources.

The dispute reflects a broader, heated debate in Germany over how to reduce dependency on China, its top trading partner, after Russia's invasion of Ukraine highlighted the dangers of reliance on an increasingly assertive, authoritarian state.

China has urged Germany not to politicize the countries' economic relations or engage in protectionism "in the name of national security".

In a parliamentary hearing that touched on an array of security matters, the heads of the German foreign and domestic intelligence agencies said they could not deliver a public assessment of Cosco's bid but in general urged caution.

"We are very, very critical of the participation of China in critical infrastructure," the head of the foreign intelligence service (BND), Bruno Kahl, told a parliamentary hearing, noting that a port should be considered critical infrastructure, so any possible investment should be very carefully reviewed.

Germany should expect China to use technology, including 5G infrastructure, or economic power to implement its ideas, he added. "In the case of a political disagreement between China and Germany, these instruments will be used," he said.

The head of Germany's domestic intelligence service, Thomas Haldenwang, said stakes in critical infrastructure could also open the door to sabotage and influence on public opinion.

"When I speak with foreign partners about China, they always say: Russia is the storm, China is climate change," he said.

"So we are going to have to brace for this climate change in the coming years."