The apparent abduction of Vietnamese businessman Trinh Xuan Thanh in Berlin has triggered a diplomatic spat between Germany and Vietnam.

Berlin police confirmed to DW that a Vietnamese citizen is thought to have been kidnapped in the city on July 23, but they declined to offer any more details on the ongoing investigation.

And in a statement to Berlin's taz newspaper, Thanh's lawyer Petra Schlagenhauf said that her client had been forcibly abducted around 10:40 a.m. while on the street near Berlin's centrally located Tiergarten park.

But Vietnamese media, citing the country's Ministry of Public Security, reported on Monday that Thanh had voluntarily given himself up in Hanoi to criminal investigators, who had been searching for him since April.

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The German Foreign Ministry reacted with considerable anger to the reports. "Now that there are no longer any serious doubts about the involvement of the Vietnamese services and the Embassy of the Socialist Republic of Vietnam in Berlin, the state secretary in the Foreign Ministry, Markus Ederer, yesterday summoned the ambassador," a Wednesday statement said. "The kidnapping of Vietnamese citizen Trinh Xuan Thanh on German soil is an unprecedented and blatant violation of German law and international law."

The ministry went on to say that the incident had "the potential to massively negatively impact relations between Germany and … Vietnam." As a first step, the official representative of Vietnam's intelligence agency in Germany was to be "declared persona non grata" and given 48 hours to leave the country.

Dissidents are suffering a crackdown in Vietnam

The government admitted that Vietnam had asked Germany to extradite Thanh during last month's G20 summit in Hamburg. Germany is now demanding that Thanh be returned to Germany so that both an application for extradition and Thanh's application for asylum can be considered and processed in the proper legal fashion.

'Great pity'

Vietnam's foreign ministry on Thursday rebuked the claims made by their German counterparts.

"I feel sorry about the statement on August 2 of the German foreign ministry spokesperson," Vietnamese foreign ministry's spokeswoman Le Thi Thu Hang told reporters in Hanoi. "Vietnam very much respects and wants to develop the strategic partnership relation between Vietnam and Germany."

Kidnapped or pressured?

Viet Tan, an unsanctioned Vietnamese pro-democracy party, expressed some surprise at the boldness of Vietnam's move. "Abducting dissidents is something that Vietnamese intelligence would more likely attempt in Southeast Asia," spokesperson Duy Hoang told DW by email. "It's practically unheard of happening in the West. The German government needs to condemn this brazen action in the strongest terms. The kidnapping of Trinh Xuan Thanh comes amidst a widespread crackdown by the Vietnamese communist authorities."

Though the Vietnamese media did not mention a kidnapping, Tran Quoc Thuan, a former member of the country's National Assembly, told the BBC on Tuesday that he was "surprised" to hear that Thanh had returned to the country.

He also speculated that Thanh was pressured into returning to Vietnam and confessing, rather than actually having been kidnapped, though Thuan added, "The possibility of kidnapping is higher."

Anti-corruption as a political weapon

The 51-year-old Thanh was a political functionary in Vietnam for many years before being stripped of all posts amid corruption accusations in September 2016. In a communist country where business and politics are closely integrated, Thanh was chairman of the board of the state's Petro Vietnam Construction Joint Stock Corporation (PVC) and held a number of leading positions in state companies while simultaneously holding a seat in parliament.

The conservatives currently have the upper hand in Vietnamese single-party politics

According to taz, Thanh also spent some time in Germany in the early 1990s and even applied for asylum, but returned to Vietnam voluntarily to begin his career.

Vietnamese outlet Vietnamnet reported this week that Thanh was accused of "property misappropriation" by selling shares of a state company at a lower price than they were actually valued at and then pocketing the difference. Some 10 former PVC employees are being prosecuted as part of the investigation, the news outlet said.

But there are plenty of other reasons why authorities may be pursuing Thanh, whose whereabouts had been the subject of speculation for some time. In an interview he gave to a Berlin-based Vietnamese blog a few months ago, Thanh said he was part of a wing of the ruling Communist Party of Vietnam (CPV) that had become dangerous to former president and current party leader Nguyen Phu Trong. Thanh also used the blog to threaten to shed light on the power structures in Vietnamese politics.

There have been signs of a power struggle within the CPV between conservative communists and pragmatic capitalist reformers for some time, with the conservatives currently enjoying the upper hand. Much like in China, anti-corruption campaigns have become a preferred method for weeding out political opponents. Dozens of high-ranking Vietnamese government and party officials have been arrested in the past few months - and some sentenced to death.