The EU is developing plans to require airlines to track and report their contribution to climate change from January 2025 - not only from carbon dioxide, but also soot, nitrogen oxides and water vapour.

Airlines' non-CO2 emissions have at least as important an impact on global warming as their CO2 output, according to the EU's aviation safety authority.

A draft Commission proposal for the new rules, seen by Reuters, would exclude international flights - defined by the EU as those departing or landing in Europe from non-European destinations - from the emissions disclosure rules for two years, limiting them until 2027 to only flights within Europe.

"Such reporting shall only be required in respect of routes involving two aerodromes located in the European Economic Area," it said, adding that flights from the EEA to Switzerland or Britain would also be covered.

It did not give a rationale for the exclusion. The exemption mirrors current EU rules that require airlines to disclose and pay fees for their CO2 emissions produced on flights only inside Europe, although those rules are due to be reassessed in 2026.

The proposed new rules have split the industry, with lobby group the International Air Transport Association seeking an exemption for long-haul flights, while low-cost European carriers Ryanair and Easyjet say all flights - including long-haul international trips - should be included.

IATA has said it is not currently possible to accurately monitor a flight's non-CO2 emissions, and that the EU's emissions monitoring requirements should be voluntary and exempt international flights.

"Any intention of expanding the scope to extra-EU international flights would raise legal concerns," IATA director general Willie Walsh said in a letter to the European Commission in April, seen by Reuters.

The European Commission did not immediately respond to a request for comment.