The European Union will maintain its carbon tax imposed on airlines operating in its airspace, the Danish climate minister said, despite a freeze in purchases of Airbus aircraft by China.

As long as an international policy on carbon emissions on airlines does not exist, the "EU will stick to its own ETS system", Martin Lidegaard said on Friday. Denmark currently holds the EU's rotating presidency.

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

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

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

The head of the Airbus parent company EADS said on Thursday that China has delayed purchases of Airbus planes in reaction to the disputed tax.

"Airbus is subjected to retaliation measures," EADS chief executive Louis Gallois, told a news conference as he presented annual results.

Airbus spokesman Stefan Schaffrath said 35 orders by Chinese airlines for A330 planes are on hold.

He said orders for another 10 A380 superjumbos are also under threat, and that the combined value of the planes is $12 billion.

"The economic impact is real," he said.

Schaffrath insisted that Airbus is working to reduce emissions but argued that a Europe-only measure will result in trade imbalance.

"Our sector is committed to green aircraft," he said. "We truly believe that the global issue of emissions does not know boundaries, and we need a global solution."

The head of the International Air Transport Association warned on Tuesday that the EU tax could provoke trade wars.

"The government has forbidden all national airlines to sign agreements with the European Union and our stance is in line with the authority's," Chen Feng, chairman of the HNA Group, parent company of the Hainan Airlines Co.

"The EU's unilateral agreement cannot work and I forecast it will fizzle out," Chen said.

Zhou Dadi, former director of the energy research institute of the National Development and Reform Commission, said the new EU carbon-trading scheme could add new income to the EU and help it deal with its fiscal difficulties, but it won't lead to breakthroughs in aviation technology since very few companies are capable of advanced R&D, he said.

"If the EU sticks to the scheme without considering others' opinions, the consequences will be unbearable for EU," said Li Xiaojin, professor at Civil Aviation University of China.

"I think all Chinese will support the government's decision to fight the EU's unilateralism, which is illegal If orders for Airbus planes are canceled, I think no one in China will raise objections, either," Li said.

The EU's new scheme violates the Chicago Convention on International Civil Aviation and the principle of "common but differentiated responsibility" in the United Nations Framework Convention on Climate Change, Su Wei, director-general of department of climate change under the National Development and Reform Commission.

"China opposes any kind of unilateral measures and trade barriers by using climate change as an excuse. We hope the issue will be solved through consultation, resulting in a fair, global solution," Su said.

Lan Lan and Xin Dingding in Beijing contributed to this story.