Airlines 'are conforming' with EU rules on emissions
The vast majority of airlines have conformed with EU rules on reporting carbon dioxide emissions, the European Commission has said.
From next year, aircraft emissions will be included in the EU carbon market in an attempt to increase efficiency.
The EU required airlines to report by March on 2011 emissions as a "dry run"; all did, bar 10 from China and India.
The issue is controversial, with China telling airlines not to take part and US firms mounting a legal challenge.
Some commentators have suggested the outcome could be a full-scale trade war, even though the measure will add only about $3 to the price of a trans-Atlantic flight.
The EU has said it will suspend the requirement to include all flights beginning or ending in the EU in the Emission Trading Scheme (ETS) if other countries can agree a genuinely global mechanism that will charge airlines for the contribution they are making to global warming.
Although aviation accounts for only about 2% of global CO2 emissions, it is the fastest-rising sector, and there are fewer technical options for constraining emissions than in areas such as electricity generation, home heating and land transport.
The requirement for airlines to report 2011 emissions by March this year was a dry run for next year, when the 2012 emissions they report by March 2013 will enter the ETS.
Failure to comply at that stage will land the airlines with penalties of 100 euros per tonne of CO2 emitted, and a ban from EU airspace if they refuse to pay.
EU member states have sent letters to the 10 Chinese and Indian airlines that missed the 31 March deadline requiring them to submit their data by mid-June.
Financial penalties are likely to be sought if they do not.
The European Commission calculates that the 10 airlines account for only 3% of the total basket of emissions caused by flights beginning or ending in the EU.
In February, 23 countries that had debated whether to challenge the legality of the EU move under the Chicago Convention, the international aviation treaty, decided not to press ahead.
However, they have left the option open for the future.
EU climate commissioner Connie Hedegaard also revealed that emissions from sectors covered by the ETS shrank by more than 2% during the course of 2011.
"This good result shows that the ETS is delivering cost-effective emissions reductions," she said.
"It also emphasises why the ETS remains the engine to drive low-carbon growth in Europe."
However, at just under 6 euros ($7.70) per tonne, the carbon price remains far too low to drive significant investment in cleaner technology or practices.
Ms Hedegaard confirmed that the commission is seeking to withdraw a batch of pollution permits from the market in order to drive the price higher.
Follow Richard on Twitter