Poland said Friday following an investigation that Belarusian security services were behind the diversion of a Ryanair flight that resulted in the arrest of an opposition journalist onboard.
The EU member has been probing the incident as a Polish-registered plane was used for the Athens-to-Vilnius flight in May which made an emergency landing in Minsk over an alleged bomb threat.
The plane was carrying Roman Protasevich, an exiled co-founder of a popular opposition Telegram channel, and his Russian girlfriend, Sofia Sapega. The two were immediately arrested in Minsk and remain under house arrest.
Poland's special services prepared a presentation for journalists featuring air traffic control recordings and other findings from the investigation by prosecutors and the ABW counterintelligence agency.
"We have provided you with evidence and other facts which clearly indicate that the hijacking of the Ryanair plane was an operation by Belarusian special services aimed at arresting an opponent of the political regime," Stanislaw Zaryn, spokesman for the Polish services, told reporters.
The narrator of the presentation said "a (Belarusian) KGB officer issued orders to the air traffic controller in the tower in Minsk, according to recordings secured by the ABW."
Zaryn had said in a statement earlier that the KGB officer "was present in the operations room during the work of the air-traffic control tower."
"It was the officer who gave commands and made decisions concerning landing in Minsk. At the same time, the KGB officer was in phone contact with someone to whom he reported what was happening with the plane," he added.
"It must be underlined that taking control over a traffic control tower by a special services agent is something unprecedented, exceeding regulations and practice."
Zaryn added in a tweet that the conclusion of the investigation was notably based on "the testimony of a witness who was present at the air traffic control tower in Minsk."
The New York Times reported this week that an air traffic controller present in the tower had defected and was sharing what he knew with Polish investigators.
The diversion of the plane sparked an international outcry and led the European Union to impose sanctions on Belarus.
The EU believes that Minsk in turn sought to retaliate for the sanctions by engineering the Belarus border crisis which has seen thousands of mostly Middle Eastern migrants cross or try to cross the bloc's eastern border into Latvia, Lithuania or Poland since the summer.
Belarus denies this and has urged the EU to take in the migrants.