The UN civil aviation agency will launch an investigation into the May 23 diversion by Belarus of a European flight and arrest of a dissident on board, it announced on Thursday.
The International Civil Aviation Organization (ICAO) Council "decided to undertake a fact-finding investigation of this event," the statement said.
It added that, at a meeting, the body "underlined the importance of establishing the facts of what happened, and of understanding whether there had been any breach by any ICAO Member State of international aviation law."
The council "requested the ICAO Secretariat to prepare an interim report to the Council for a subsequent meeting of the current session."
Belarus's strongman President Alexander Lukashenko sparked international outrage by dispatching a fighter jet Sunday to intercept a Ryanair flight from Athens to Vilnius carrying opposition journalist and activist Roman Protasevich, 26, and his girlfriend Sofia Sapega, 23.
His parents pleaded Thursday for international help to get him released, and the G7 global powers also demanded he be freed, with the EU's foreign policy chief threatening economic sanctions.
The ICAO, of which Belarus is a member, has no power to order sanctions. But European leaders this week agreed to cut air links with Belarus and told airlines to avoid the country's airspace.
Its meeting Thursday came after Western powers on the UN Security Council called on it to investigate, echoing an earlier call from NATO.
But Russia's support for Minsk means the UN Security Council is unlikely to agree on a collective statement.