Relations with Germany look set to deteriorate further as Vietnam prepares to put on trial a former oil industry executive allegedly kidnapped from Berlin in July.
Trinh Xuan Thanh could face the death penalty if convicted on charges of embezzlement at a trial which begins on Monday.
Vietnam deported Mr Thanh’s German lawyer, Petra Schlagenhauf, when she arrived in Hanoi on Thursday in an attempt to attend the trial.
Germany summoned the Vietnamese ambassador in Berlin to demand an explanation. It has already expelled Vietnamese diplomats and downgraded relations as it continues to demand the return of Thanh to Germany.
The former boss of the construction arm of the state oil company, PetroVietnam, Trinh Xuan Thanh had been seeking political asylum in Germany, claiming that the corruption charges against him were politically motivated.
Suspected Vietnamese spies
The plot thickened last week when a Danang property tycoon, who also held a senior position in the Vietnamese intelligence service, attempted to seek asylum in Germany.
Lawyers for the agent, Phan Van Anh Vu, suggested that he could be bringing crucial evidence about the seizure of Thanh, who was seen being bundled into a car by suspected Vietnamese spies at the end of July.
However, Vu only got as far as Singapore where he was arrested for travelling on a false passport. He was quickly deported back to Vietnam.
The startling deterioration in relations between Vietnam and one of its most valued trading partners has given an international dimension to what looks like a fierce internal power struggle in Vietnam.
The General-Secretary of the Communist party, Nguyen Phu Trong, has taken observers at home and abroad by surprise with the scope and vigour of what he calls an anti-corruption campaign.
He publicly staked his reputation on the capture of the Thanh, a relatively low level official, seemingly unconcerned at the harm inflicted on Vietnam’s international reputation.
Thanh is standing trial on Monday with a number of other former senior officials from PetroVietnam, one of the key targets of Mr Trong’s campaign.
Secretive one-party system
In a country where the public and private sectors are rife with corruption, the targeting of specific sectors and patronage networks soon becomes indistinguishable from a political purge.
Many of those arrested were associated with the ambitious former prime minister, Nguyen Tan Dung, who lost out in a struggle for the party leadership with Mr Trong in January 2016.
Relations with Germany have been one casualty of the opaque ructions shaking Vietnam’s highly secretive one-party system.
Further ramifications can be expected as the Communist party leadership looks increasingly inward and shows contempt for the concerns and interests of international partners.