Bratislava (dpa) - Slovakia‘s public prosecutor is opening an investigation over the country‘s involvement in the kidnapping of a Vietnamese businessman in Berlin. The Slovak daily Dennik K reported on Tuesday that witness testimony that a Slovakian government aircraft was involved in the kidnapping made the investigation necessary. Vietnamese businessman Trinh Xuan Thanh was seized in Berlin along with a female companion in July 2017. He was taken back to Vietnam, where he subsequently received two life sentences for corruption in two separate cases. The German government claims that Vietnamese agents kidnapped Thanh in Berlin after he sought political asylum. A 47-year-old man who played a part in the kidnapping was handed a prison sentence by a Berlin court in July.Dennik K previously reported that two police officers had seen a man, suspected to be Thanh, being pulled onto a government plane in Bratislava. According to the newspaper, the two officers have now provided formal testimony to investigators.The aircraft was supposedly given to a Vietnamese delegation by the Slovakian Interior Ministry. Former interior minister Robert Kalinak, who resigned in March amid allegations of corruption, is accused of being aware of the abduction. The head of the state‘s personal protection services has also been suspended for the duration of the investigation.