The ICAO said there has been progress in its talks with Ukraine and Russia toward allowing air traffic to resume in international airspace over the Black Sea and the Sea of Azov, and that work was continuing to find a solution.
That airspace, managed by Ukraine, is off the coast of the Crimean Peninsula, which was annexed by Russia last year. The area has been a no-fly zone for international air traffic since April last year.
"We actively engage the states in that region, in particular Ukraine and Russia, to make the states to coordinate and so far I think there has been some progress but at this stage I think they still did not find a solution," said ICAO Secretary-General Fang Liu.
National aviation agencies had warned that pilots in the area might get conflicting instructions from Ukrainian and Russian air traffic controllers.
The airspace, part of a busy route for commercial airlines' long-haul flights to the Middle East and Asia, does not go over Crimea or eastern Ukraine where Malaysia Airlines flight MH17 was shot down last July.
Ukraine, which is delegated by ICAO to control that section of airspace despite Russia's control of Crimea, made a request to ICAO late last year to reopen the corridor, which is over international waters.
"We're trying to see how we can find, through the states' cooperation, a technical solution to ensure the operation of airspace of these countries that can be maintained at the safety level... (and) can facilitate international air transport operations," Liu said.
Liu also said that an ICAO website launched in April to distribute warnings about risks to aircraft in conflict zones would be reviewed at the end of the year but "most likely will be continued."