The official, who asked not to be identified because he is not authorized to speak to the media, said the idea of "common but differentiated responsibilities" was a point of conflict in four hours of debate at the governing council meeting of the International Civil Aviation Organization.

The concept of differentiated responsibilities argues that developed countries should shoulder most of the burden for cutting emissions.

In a decision obtained by Reuters, the council instructed a working group to continue its study on "market-based measures" to deal with aviation emissions and report back at the next council meeting, scheduled for June.

The decision added a new request, asking the working group to evaluate whether the measures being studied can "accommodate the special circumstances and respective capabilities of developing countries."

Montreal-based ICAO was thrust into the spotlight after the European Union proposed controversial new rules for airline carbon emissions.

The EU rules, which took effect January 1, mean that all airlines that use EU airports must pay into a carbon offset program. That stirred threats of an international trade war with the potential to disrupt global air traffic.

Late in 2011, ICAO said it would accelerate its hunt for an alternative to the EU scheme. It aims to have a draft proposal by the end of 2012.

The official said a large majority of the council voted for the decision, including the China, Russia, the United States, and the European members.

(Reporting By Allison Martell; Editing by Janet Guttsman)

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