The EU's climate commissioner played down the impact of the controversial carbon tax being imposed by the bloc on airlines, saying Friday it would cost less than a cup of coffee per passenger.

With the tax, sharply criticised by China and the United States, "a flight from Beijing to Frankfurt for example will cost around an extra two euros per passenger," Climate Commissioner Connie Hedegaard told the French daily Les Echos.

"In other words, an amount less than that of a cup of coffee at the airport," she added.

With the dispute intensifying over the tax, Hedegaard said it was important to keep a sense of proportion.

Last month plane maker Airbus, plus half a dozen airlines including British Airways, Lufthansa, and Air France wrote a letter to the British, French, German and Spanish governments warning the tax could cost them billions of dollars in lost orders and business and lead to the loss of the thousands of jobs.

A subsequent letter by French Prime Minister Francois Fillon to European Commission head Jose Manuel Barosso made similar points, noting that China had already suspended an important Airbus order.

"We, as Europeans, of course cannot let ourselves be swayed by such threats," Hedegaard told Les Echos, stressing that China's payments due under the levy this year would be only 1.9 million euros.

"That is very, very little to be bandying around such threats for," she added.

Hedegaard said Europe "was as determined as anyone to achieve an ambitious and coordinated approach at the international level" to combat global warming emissions.

"But such an accord will not be possible if certain countries who have opposed the measure up to now do not seriously change their position," she said.

The carbon tax imposed on airlines by the European Union came into effect on January 1, but carriers will begin receiving bills only in 2013 after this year's carbon emissions have been assessed.

Hedegaard's cost estimate was considerably lower than previous Commission estimates that it prompt carriers to add between 4.0 and 24 euros ($5.25 and $31.50) to the price of a round-trip long-haul flight.

More than two dozen countries, including China, Russia and the United States, have opposed the EU move, saying it violates international law.

But the EU has said the tax will help it achieve a goal of cutting carbon emissions by 20 percent by 2020 and has insisted it will not back down on the plan.