Germany has accused Vietnam of kidnapping a former Vietnamese oil executive who was seeking asylum in Berlin and taking him home to face accusations of corruption.
Berlin ordering a Vietnamese intelligence officer to leave Germany within 48 hours.
It said it was considering further action to an "unprecedented" breach of German and international law over the abduction of Trinh Xuan Thanh, who is accused of causing around $150 million in losses at a Vietnamese state firm.
Trinh Xuan Thanh. Photo: 24h.com.vn"There is no serious doubt about the participation of the Vietnamese intelligence service and embassy in the kidnapping of a Vietnamese citizen on German soil," a foreign ministry spokesman told reporters.
Vietnam's foreign ministry did not respond immediately to a request for comment.
A return following manhunt?
Police in Vietnam said this week that Thanh had turned himself in on Monday after a 10-month international manhunt. They gave no details as to why he had decided to return home and hand himself in.
The German foreign ministry spokesman said the Vietnamese ambassador had been summoned on Tuesday afternoon and that the official representative of the Vietnamese intelligence service had been ordered to leave.
He said the kidnapping "has the potential to negatively affect relations massively".
German media reported the man had been taken from the Tiergarten, a large forested park in central Berlin, by armed men on July 23.
High flyer in a Lexus
Thanh, 51, was a former high flyer in Vietnam who was accused of mismanagement and causing losses at PetroVietnam Construction JSC, part of the state energy company PetroVietnam.
He came to public attention in mid-2016 when he was found to have a luxury Lexus car with a government license plate, causing an outcry in a country where officials are expected to live modestly.
That prompted the head of the Communist Party, Nguyen Phu Trong, to order an investigation into his career and how he had been given further promotions despite the alleged losses at PetroVietnam Construction.
Thanh took sick leave last year and went abroad, vanishing from the public eye until now.
In September, Vietnam issued an international arrest warrant for Thanh, saying it would find him wherever he was. It expelled him from the Communist Party.
The investigation at PetroVietnam has caught up many government officials and executives. Another former executive of PetroVietnam was thrown out of the politburo and demoted earlier this year.
Both the anti-corruption drive and the biggest crackdown on activists in years come at a time of internal manoeuvring within the Communist Party after the balance shifted in favour of security minded conservatives early in 2016.
Germany is Vietnam's biggest trading partner in the European Union, whose countries are due to consider approving a free trade agreement with the Southeast Asian country, one of the region's fastest growing markets.