The European Union should immediately withdraw the carbon tax it began imposing on airlines beginning with the new year, India's environment minister said.

Indian Environment Minister Jayanthi Natarajan warned EU Commissioner for Climate and Energy Connie Hedegaard in a letter the carbon emissions tax demanded from international airlines using European airspace is illegal and will hurt future climate-change negotiations, the Indian business news daily Mint reported Monday.

A copy of the letter, sent by Natarajan Dec. 28, was obtained by the newspaper.

In it, the Indian minister said the action taken under the EU's Emission Trading Scheme isn't valid.

"I strongly urge the EU to reconsider and reverse the decision to apply the scheme to non-EU airlines," he wrote, adding, "India strongly feels that a unilateral measure as the one proposed to be taken by EU, stands not only in violation of the principles and provisions of the (international) convention but will also not augur well for the success of future climate change negotiations."

India, China and the United States have led the opposition to the airline carbon tax, which came into effect Jan. 1. Under its provisions, the EU requires airlines flying to or from Europe to obtain certificates for carbon dioxide emissions.

While many airlines will be given free tax credits this year, they will eventually have to begin buying or trading credits in the future.

India and other opponents say the requirement is moot because it hasn't been negotiated as part of any international air services agreement and violates the Convention on International Civil Aviation, also known as the Chicago Convention, which is enforced by the United Nations and sets air travel rights.

The opponents also contend the new carbon tax violates the Kyoto Protocol on climate change as well as the EU-U.S. Open Skies Agreement.

Those arguments, however, were rejected last month by the European Court of Justice, which threw out a challenge from U.S. carriers and ruled the EU was within its rights to impose the tax.

"Application of the emissions trading scheme to aviation infringes neither the principles of customary international law at issue nor the Open Skies Agreement," the court ruled.

India has asked airlines such as Air India, Jet Airways (India) Ltd. and Kingfisher Airlines Ltd. to refrain from turning over carbon emissions data to the EU. New Delhi contends the emissions tax will cost the carriers $57 million in 2012.

Isaac Valero-Ladron, spokesperson for Hedegaard, told Mint the commissioner had received Natarajan's letter and is preparing a reply.

"Our law gives all countries, including India, the choice to reduce aviation's carbon pollution differently," he said. "If India takes equivalent measures, all incoming flights from India can be exempt from the EU law when arriving in or departing from Europe."

China is also protesting the EU move, The Telegraph reported.

Foreign Ministry spokesman Hong Lei said last week Beijing "opposes the European Union's unilateral legislation. China has expressed to the EU our deep concern and opposition many times on a bilateral level."

Chinese airlines have promised to file suit against the EU directive.

Chai Haibo, an official with the China Air Transport Association, told the Communist Party newspaper People's Daily in November his group will sue the EU in Germany over its provisions.