The UN's aviation body said it did not have the authority to close global air routes, seeking to distance itself from responsibility after the downing of a Malaysian airliner over Ukraine.
Malaysia's Transport Minister Liow Tiong Lai said earlier that the Montreal-based International Civil Aviation Organisation (ICAO) had shut the route after the Malaysia Airlines jet was brought down in eastern Ukraine on Thursday.
"ICAO does not open or close routes. We do not have an operational role," said chief ICAO spokesman Anthony Philbin.
The organisation did issue a warning to airlines in April about flying over Crimea in the wake of the Russian invasion but it cited potential problems with conflicting air traffic controllers, not the risk of violence.
The warning, not an order, said "consideration should be given to measures to avoid the airspace". It did not issue a warning for eastern Ukraine where pro-Russian rebels are fighting Ukrainian forces.
Malaysia said the ICAO had approved the route but this appeared to be a misreading of what the body does. ICAO issues advisories based on decisions taken by delegates rather than telling members what to do.
"It is up to countries to implement them or not, most countries do … but ICAO standards are more or less equivalent to a treaty, you can either comply or not as you see fit," said a Canadian expert on aviation law.
Despite having expertise in aviation, the ICAO is challenged by its inherent structure as a United Nations body with 190 members, said John Saba, a lecturer at McGill University's Integrated Aviation Management Programme in Montreal.
"The political constraints are beyond them," Saba said of the ICAO. "You have people from different countries who are trying to represent the interest of their country but also hammer out deals."
Ukraine had allowed airliners to fly at 9,753 metres and higher above the area where the flight came down. US and other officials said the jet was shot down by a surface-to-air missile.
Brussels-based Eurocontrol is the agency responsible for coordinating European airspace. It and the ICAO were cited in a safety bulletin issued by the European Aviation Safety Agency in April advising that Crimean airspace should be avoided.
Domestic authorities also have significant powers. The US Federal Aviation Administration issued an order on Thursday prohibiting American aircraft from flying over eastern Ukraine.
The tragedy highlights the fragmented nature of global aviation regulation.
"The countries that are members of ICAO have to agree to it. How are you going to get them all to agree to give ICAO more power over them?" said Saba.