HANOI (REUTERS) - Vietnam's state television broadcast images on Thursday (Aug 3) of a former oil executive saying he had voluntarily returned home to face justice for corruption after Germany said he was abducted in Berlin and taken back by force.

The German foreign ministry said on Wednesday that Vietnam had seized Trinh Xuan Thanh, 51, a former official at state oil company PetroVietnam, who is accused of financial mismanagement that caused losses of around US$150 million (S$200 million).

In response, Berlin ordered a Vietnamese intelligence officer to leave Germany within 48 hours and demanded that Thanh be allowed to return to claim asylum. Germany said it was considering other measures against Vietnam.

Thanh, 51, a former high flyer in the Vietnamese oil industry, appeared on state television looking tired, dressed in a polo shirt and with his hair tousled.

It was unclear if he was speaking freely.

"I wasn't thinking maturely and decided to hide and during that time I realised I need to return to face the truth and... admit my faults and apologise," Thanh said in a prime-time bulletin on Vietnam Television.

"I decided out of fear to hide in Germany, where I lived a precarious and anxious life," television quoted Thanh as saying in a signed confession dated July 31.

"I returned to Vietnam and presented myself to the investigative authority."

Police said he had turned himself in on Monday after a 10-month international manhunt.

His lawyer ruled out that version of events.

"He would never have done that. He was scared of going back and what the consequences might be," his asylum lawyer in Germany, Victor Pfaff, told Reuters.

He said witnesses had described how armed men violently bundled a man and a woman into a car with Czech registration plates outside the Sheraton hotel in western Berlin.

German officials say the account of the kidnapping - which media have compared to Soviet abductions before the fall of the Berlin Wall in 1989 - is plausible.

The foreign ministry blamed the Vietnamese intelligence service and embassy for what it called an unprecedented and glaring breach of German and international law.

Vietnam's foreign ministry expressed regret over a statement from Germany accusing Vietnam of kidnapping him.

"Vietnam very much respects and wants to develop the strategic partnership relation between Vietnam and Germany," foreign ministry spokeswoman Le Thi Thu Hang told reporters in Hanoi.

It was not clear whether Thanh had legal representation. Closed-door trials are common in Vietnam where the one-party state keeps a tight clamp on dissent.

An anti-corruption drive and the biggest roundup of dissidents in years follow a shift within the party leadership last year towards security-minded conservatives.

OUTCRY OVER LEXUS

Thanh was an executive 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.

Communist Party chief Nguyen Phu Trong ordered an investigation into his career and how he had been promoted despite alleged losses at PetroVietnam Construction.

Thanh took sick leave last year and went abroad, vanishing from the public eye until now.

Germany's Sueddeutsche newspaper reported he had requested asylum after his arrival in Germany and had been due to appear at a hearing about the request on July 24.

His asylum application was not completed and was still being processed, the foreign ministry in Berlin said on Thursday.

Some residents in Hanoi said they could not access social networks, including Facebook, Instagram and Twitter late on Wednesday and early on Thursday, but they said the sites were now back to normal.

It was not immediately clear why the social network platforms were inaccessible and whether it was in relation to Germany's accusations.

It is not unusual for social media to be temporarily closed in Vietnam where authorities often censor news.

Nguyen Quang A, a retired computer scientist and vocal government critic, said on his Facebook page someone had tried unsuccessfully to hack his account 16 times early on Thursday.

He said the kidnapping was "stupid" and would cause severe diplomatic consequences.

Other activists have also publicly criticised the government over the kidnapping allegations.