The EU on Tuesday urged nations to accept a compromise on plans to curb airline carbon emissions at a key UN conference, though resistance to striking an overall deal remains fierce.

"We believe a solution is now in sight," said the spokeswoman for EU Transport Commissioner Siim Kallas.

Kallas was set to make a plea for an EU-led pollution-cutting scheme later Wednesday at the International Civil Aviation Organisation (ICAO) in Montreal, the UN agency that sets global aviation standards.

"A truly global deal is long overdue and the world justifiably expects an agreement," the spokeswoman said.

But several nations -- including the United States, India and China -- have balked at a global emissions scheme for airlines and fought fiercely against a 2012 plan launched by Brussels that threatened to tip into a trade war.

Under the EU's ill-fated arrangement, airlines flying in EU airspace were required to buy pollution credits to cover 15 percent of their CO2 emissions for the entire flight, wherever it originated.

But 26 of the ICAO's 36 members opposed the move, saying the levy violated international law.

At the time, plane maker Airbus, plus half a dozen major European airlines, warned that the tax could cost them billions of dollars in lost orders and business and lead to the loss of the thousands of jobs.

Faced with the storm of criticism, last year the EU suspended its CO2 Emissions Trading Scheme (ETS) for intercontinental flights, saying it wanted to give all sides more time to reach a global accord.

In suspending its programme, the Commission on Tuesday said it had done its part to "avoid a trade war" and that it was now up to other countries to do their part.

A European source said earlier this month that the EU is ready to compromise over its tax if opponents, led by the United States and China, apply a similar levy by 2016.

In the new offer, airlines would be subject to the EU tax only for the portion of flights that pass through European airspace.

In the runup to the conference, on Monday the International Air Transport Association warned that a piecemeal approach to battling aircraft carbon emissions could lead to trade feuds.

But IATA general manager Tony Tyler said he was "optimistic" that countries will come together on a plan.