Germany has ordered the expulsion of a second Vietnamese diplomat and suspended the strategic partnership between the two countries in response to the suspected abduction of a former Vietnamese official.
The German government said it had evidence that Trinh Xuan Thanh was kidnapped by Vietnamese agents in central Berlin in July, describing the action as “totally unacceptable” and “a gross violation of international law”.
Germany has warned that it could take further steps if Vietnam continues to ignore its demands over the case.
Mr Thanh was shown on television in Hanoi, saying that he had turned himself in voluntarily, just a week after he was bundled into a car by armed men in Berlin.
He is facing trial on corruption charges related to his time as chief executive of the construction arm of the state oil company, PetroVietnam.
Germany demanded his return and expelled an intelligence officer from the Vietnamese embassy in early August.
It says Vietnam has made no effort to meet its continuing demands for an apology, a promise not to repeat the violation, and for an investigation into the circumstances of the case.
The Vietnamese action took many diplomats by surprise given the value the Communist authorities have put on close economic and strategic ties with Europe’s largest economy.
Germany is well placed to block the ratification of the EU-Vietnam trade deal signed in 2015 should Hanoi continue to resist its demands.