The International Court of Justice on Tuesdayunanimously rejected anappeal by four Middle East nationsagainst a decision by the world civil aviation body in favour ofQatarover sovereign airspace.
Bahrain, Egypt, Saudi Arabia and the United Arab Emirates had imposed an air blockade against Doha after accusing it of backing radical Islamists and Iran.
The decision by Hague-based court covers a key part of the standoff that erupted three years ago pitting the four nationsagainstQatar.
The court also "holds that the International Civil Aviation Organisation (ICAO) has jurisdiction" in the case, by 15 judges to one, ICJ President Abdulqawi Ahmed Yusuf said.
The ICAO in 2018 ruled it had the jurisdiction to handle a dispute brought byQatar, which accused its neighbours of violating a convention that regulates the free passage of its passenger planes through foreign airspace.
But the four allies disagreed, saying the ICAO was not the right body to judge in the dispute and that its decision to do so was "manifestly flawed and in violation of fundamental principles of due process and the right to be heard."
They had asked the ICJ to declare the aviation body's ruling "null and void and without effect."
There was no immediate reaction fromQataror its four rivals.
Saudi Arabia, Bahrain, the UAE and other allies abruptly severed ties withQatarin June 2017, accusing the gas- and oil-rich country of backing radical Islamists and Iran.
They imposed wide-ranging punitive measures including banning Qatari planes from their airspace, closingQatar's only land border with Saudi Arabia and expelling Qatari citizens.
Doha strongly denies the allegations.
The countries justified the moves against the Gulf peninsula state saying it was their sovereign right to protect their national security.
Qatarfiercely rejected the claims that it had violated a series of agreements inked with its neighbours in 2013 and 2014 aimed at settling years of diplomatic rancour.
(With inputs from AFP)