WOLFSBURG, Germany (Reuters) - Foreign Minister Sigmar Gabriel said on Friday Germany was considering measures against Vietnam for kidnapping a former oil executive and described the abduction, denied by Hanoi, as reminiscent of Cold War spy movies.

An image of Vietnamese former oil executive Trinh Xuan Thanh is seen on a TV screen on state-run television VTV, saying he turns himself in at a police station in Hanoi, Vietnam August 3, 2017. REUTERS/Kham

Germany says Vietnamese businessman Trinh Xuan Thanh, 51, was seized in Germany and spirited to Vietnam where he is suspected of corruption and causing around $150 million in losses at a Vietnamese state firm.

Hanoi says he returned home voluntarily.

Thanh “was taken out of Germany using methods which we believe one sees in thriller films about the Cold War. And this is something that we cannot accept,” Gabriel told a news conference

Gabriel, speaking after talks in Wolfsburg with Slovak Foreign Minister Miroslav Lajcak, said Germany was considering punitive measures against Vietnam, but did not elaborate.

He said Germany had asked a Vietnamese intelligence officer at the embassy in Berlin to leave. A foreign ministry source said it assumed the officer had left Germany after Berlin on Wednesday set a 48-hour deadline for his departure.

“We demanded that he leave because we strongly believe he is a person who was involved in kidnapping,” Gabriel said. German media say Thanh was seized in Berlin on July 23.

“Everything supports this assumption that he, with the help of the Vietnamese secret service and using his residence in the Vietnamese embassy in Germany, abducted a person who had asked for asylum,” Gabriel added.

Vietnam says Thanh, a former official at the Vietnamese state oil company who is accused of corruption, returned home of his own free will.

Germany is Vietnam’s biggest trading partner in the European Union, which is considering approval of a free trade agreement with the Southeast Asian country, one of the region’s fastest growing markets.

Vietnamese officials had requested Thanh’s extradition on the margins of the G20 summit, when Prime Minister Nguyen Xuan Phuc met German Chancellor Angela Merkel.

Germany earlier this week demanded that Thanh be allowed to return to Germany to claim asylum.

Vietnamese state television on Thursday broadcast images of Thanh looking tired and he was quoted as saying that he had turned himself in.

His lawyer in Germany ruled out this version of events, adding that 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.

The German newspaper Berliner Zeitung on Friday quoted the attorney as saying there were indications that Thanh had been transported via ambulance to an unnamed eastern European country, and was then flown to Vietnam.