Authorities in Germany are investigating whether China maintains an illegal extraterritorial police station in Frankfurt, a spokesperson said, a week before Chancellor Olaf Scholz heads on an already contested visit to the economic giant.
The Chinese embassy did not immediately respond to a request for comment.
A spokesperson for the interior ministry in the German state of Hesse said police and internal security services were checking a report by Spanish activist group Safeguard Defenders, who said China had set up undeclared police offices in 30 countries, including Germany.
Confirming an earlier report in the Frankfurter Allgemeine newspaper, the spokesperson said they so far had no indications such facilities existed in Frankfurt.
Germany prospered for two decades from China's insatiable demand for German machine tools, but Russia's invasion of Ukraine has prompted soul-searching over the longer-term costs of economic ties with authoritarian countries.
Scholz has faced criticism from foreign allies and from within his own government over his decision to allow the sale of a minority stake in a terminal at Hamburg, Germany's largest port, to a Chinese state company.
Next Friday's trip to China, where Scholz will be accompanied by a delegation of bosses from Germany's biggest companies, has also been criticised by political opponents who say Berlin must learn lessons from the failure of a past policy of engagement with Russia to deter President Vladimir Putin.
Dutch authorities on Wednesday said they were investigating Chinese offices that were operating illegally in the Netherlands, carrying out tasks like renewing driving licences.
That followed allegations, denied by the Chinese embassy in The Hague, that the office had also harassed a Chinese dissident living in the Netherlands.
(Reporting by Kirsti Knolle, writing by Thomas Escritt, Editing by William Maclean)