The European Union on Tuesday gave China and India a month to comply with a new airline carbon emissions fee coming into effect across the bloc, or face penalties for flights in and out of Europe.

EU Commissioner for Climate Change Connie Hedegaard said all EU airlines and "nearly all" world airlines had agreed to hand over emissions data required under a controversial carbon levy on air travel that took effect January 1.

"There has been a very, very high level of compliance ... the only exception is Chinese and Indian carriers," she said at a news conference.

While some 1,200 airlines had complied with the EU requirements, eight Chinese and two Indian airlines representing less than three percent of aviation emissions in the 27-nation bloc had refused.

"They have been given till June to report back their data," she said.

Asked what would be the consequences should they fail to respond by June 15, Hedegaard said "if there is no data by the mid-June deadline then it will be up to member states to apply penalties."

The two Asian giants have attacked the EU scheme, calling it a unilateral trade levy disguised as an attempt to fight climate change. India last month barred its airlines from complying with the EU carbon tax, joining China in resistance.

The EU says the tax aims to help it achieve a goal of cutting emissions by 20 percent by 2020 and has said no airline will face a bill until 2013 after this year's carbon emissions have been tallied.

It says the cost for the airlines is manageable, calculating that the scheme could force the carriers to add between 4.0 euros ($5.50) and 24 euros to the price of a long-haul round-trip.

But industry insiders have expressed concern that the scheme could spark a trade war between the EU and the countries opposed to the tax.