A group of 26 countries has signed a formal protest note over the EU’s controversial Emissions Trading Scheme (ETS).
Members of the UN’s International Civil Aviation Organisation (ICAO) executive council described the scheme as “discriminatory” and a violation of global laws.
After a two-day meeting in New Delhi, India, the group agreed to send a formal protest to the EU, Reuters reported.
The group includes the US and China which have long made their opposition to ETS clear.
Under the EU scheme, aviation will be included in the ETS when it comes into force in January.
This will require all airlines flying into or out of EU airports to have permits to cover all the CO2 they emit during the entire flight.
The latest protest is part of a growing chorus of opposition to the scheme. The International Air Transport Association (IATA) last week called on the EU to “abandon” its plan to include aviation in ETS.
The Association of European Airlines (AEA) has warned there could be a backlash if the EU goes ahead.
In a statement, ICAO said: "There was wide concern expressed by all countries present, without exception, that the unilaterally imposed EU (emissions trading scheme) measures were inconsistent with the international legal regimes.
"The legal infirmities in the EU laws were pointed out. It was stated by the various delegates that they were also discriminatory (to) carriers."
ICAO said the issue of aviation in ETS is on the agenda for the 190-nation body's next meeting in November.
The group of 26 countries is expected to submit a working paper along with their joint declaration in opposition of the scheme.
Critics, including the 26 opposing governments, have called the "unilateral" scheme illegal, saying it violates the Chicago Convention on international aviation as well as some provisions under the World Trade Organisation (WTO).
Three US airlines are currently challenging the EU plans in Europe's highest court, which is due to give its first opinion on the case on October 6, Reuters reported.
But the agency said there were no signs the EU was changing track. It quoted a spokesman as saying: "The EU is not considering backing down."