The US Justice department charged four Belarus officials with air piracy Thursday for last year's forced diversion of a Ryanair flight in order to arrest a dissident on board.

Two top officials of the state air navigation authority and two security officials were accused of conspiracy to commit aircraft piracy for allegedly taking part in a fake bomb scare scheme to force the aircraft to land in Minsk on May 23, 2021, so that the Belarusian government could seize opposition campaigner Roman Protasevich.

The charges, filed in federal court in new York, said Ryanair Flight 4978 from Athens to Vilnius had been carrying more than 100 passengers, including four US citizens, when Belarus authorities concocted the scheme to force it to land.

Two of the four charged, Leonid Mikalaevich Churo and Oleg Kazyuchits, are director general and deputy director general, respectively, of the state aviation authority Belaeronavigatsia.

Two others from the state security services, their names not fully known to the FBI, were also charged.

"The FBI identified a detailed operation that subjected passengers from many countries, including the US, to the realities of terroristic threats," said FBI Assistant Director Michael Driscoll.

"Not only is what took place a reckless violation of US law, it's extremely dangerous to the safety of everyone who flies in an airplane," he said.

"The next pilot who gets a distress call from a tower may doubt the authenticity of the emergency -- which puts lives at risk."

The United States has charged four Belarus officials with air piracy over the diversion of a Ryanair flight in May 2021 in order to arrest a dissident. The United States has charged four Belarus officials with air piracy over the diversion of a Ryanair flight in May 2021 in order to arrest a dissident. Photo: AFP / PETRAS MALUKAS

The diversion operation was led by state security services and succeeded in having Protasevich, 26, a journalist with the Nexta opposition media, and his girlfriend Sofia Sapega, a law student at the European Humanities University in Lithuania, arrested at a Minsk airport.

Both were placed under house arrest to face various charges.

According to the US indictment, Churo and the security officials communicated the ostensible bomb threat to traffic officials at Minsk Air Control Center even before the Ryanair flight took off from Athens, demanding it divert to Minsk.

They waited until the plane entered Belarus air space to alert the aircraft to the purported bomb threat, in order to force it to land in Minsk.

Churo's deputy Kazyuchits then sought to have the incident record falsified to hide the fabricated bomb threat and the involvement of security officials, according to the indictment.

The four, who remain at large in Belarus, all face possible life in prison if they are brought to justice in the United States.

The incident sparked international outrage and has brought punitive sanctions from Europe, Canada, Britain and the United States.

The International Civil Aviation Organization on Monday said it had completed its investigation but would only reveal the conclusions at the end of this month.