The United States and Western European members of the UN Security Council called Wednesday for the International Civil Aviation Organization to urgently investigate Belarus’ diversion of a commercial flight to arrest an opposition journalist on board.

In a statement after a Security Council meeting they called the incident “unprecedented and unacceptable” and demanded “full accountability for those responsible.”

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“These acts are a blatant attack on international civilian aviation safety and on European security and show flagrant disregard for international law,” they said.

They also called for Belarus to immediately release the journalist, Roman Protasevich, and his girlfriend Sofia Sapega who was also on the flight and arrested.

“We fully condemn this as yet another blatant attempt by the Belarusian authorities to silence all opposition voices,” said the statement signed by Estonia, France, Ireland, Belgium, Germany, Norway, Britain and the United States.

The statement came after a closed meeting of the UN Security Council on the matter.

According to a diplomatic source, Russian ambassador Dmitry Polyanskiy called the claims of the Europeans and the United States “fake news.”

Asian and African countries on the council did not add their names to the statement.

Protasevich was aboard a Ryanair flight from Athens to the Lithuanian capital Vilnius when it made an emergency landing in Minsk after Belarus President Alexander Lukashenko ordered it down and a Mig-29 fighter jet was mobilized to follow the aircraft.

European leaders have accused Minsk of essentially hijacking the passenger flight.

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Russia, a strong supporter of Lukashenko, maintains that the aircraft landed in Belarus due to a bomb threat.

The Montreal-based International Civil Aviation Organization is expected to meet on Thursday over the incident.

“ICAO is strongly concerned by the apparent forced landing of a Ryanair flight and its passengers, which could be in contravention of the Chicago Convention,” the organization said on May 23, referring to the 1944 agreement establishing the principles of international air transport.