A diplomatic dispute has broken out between China and Belgium, amid rising concerns over Beijing's involvement in European infrastructure.

According to a leaked diplomatic cable, seen by POLITICO, a Chinese official demanded that Belgian Foreign Affairs Minister Hadja Lahbib "retract" an interview in which she cited warnings that China's commercial ships could be "converted into warships for military equipment.”

A couple of days after the interview, a diplomat from the Chinese Embassy in Belgium met with a Belgian foreign ministry official at the request of the Chinese, according to the cable. The diplomat criticized the accusations from Lahbib that China would be disguising military ships as civil ships and stressed that the minister shouldn’t listen to “rumors." China then asked Belgium to retract the interview, which the foreign affairs ministry declined to do.

In a thinly veiled threat, the Chinese diplomat also pointed out that trade between Chinese and Belgian ports is lucrative for Belgium. The Belgian government should respect that economic activity if it wants this to continue, the diplomat added.

The leak provides a rare glimpse into the worsening tensions between Europe and China that normally stay hidden from view in the closely guarded world of diplomatic relations.

It comes at an increasingly fraught time, with mounting unease in European capitals over China's investment in ports and other critical infrastructure.

Jonathan Holslag, a professor at the Free University of Brussels, recently warned about the role of the Chinese maritime sector in the Belgian ports.

Lahbib referred to Holslag’s report in the interview with Belgian media earlier this month. “You have also read how Chinese merchant ships can be converted into warships for military equipment,” Lahbib said.

When asked whether Belgium should tackle the investments of Chinese shipping company Cosco, she said her country should think about it and that “together with the rest of the EU, we have to reduce our strategic dependency on China.”

The German government recently reached an agreement on a controversial deal for Cosco to buy a stake in one of the terminals at Hamburg, a strategic commercial port on the mouth of the Elbe River.

EU countries are ringing the alarm bells over Beijing, just as Chinese President Xi Jinping secured an unprecedented third term as leader of China’s Communist Party. Concerns are growing in the West that China's alliance with Russia poses a major long-term strategic threat.

But there is little agreement between EU governments over how to handle relations with the Chinese. German Chancellor Olaf Scholz, for example, favors continuing close engagement and is making a trip to Beijing next week. Others believe that approach risks repeating the mistakes Germany made of becoming too reliant on Russia for energy.

At last week’s European Council summit, even EU leaders who shied away from direct parallels between Russia and China still argued the EU should reduce its current dependencies on China. On the margins of that meeting, Belgian Prime Minister Alexander De Croo admitted to reporters that European countries in the past had been “a bit too complacent” regarding China.

The Chinese involvement in Belgium is a case in point. In contrast to Hamburg and the Greek port of Piraeus, there was little discussion when Cosco, in 2017, became a majority shareholder of a container terminal in the Belgian port of Bruges.