* U.S. objects to EU carbon plan, seeks to exempt airlines
* EU says won't back down
(Updates with U.S. quotes, adds background)
By Alister Doyle, Environment Correspondent
OSLO, June 22 (Reuters) - The United States demanded on Wednesday that the European Union exempt U.S. airlines from an EU law widening carbon permits to aviation, hardening a standoff over a scheme due to start in 2012.
After talks in Oslo, the EU insisted it would not back down on its unilateral plan to penalise greenhouse gas emissions from planes taking off and landing in the European Union as part of efforts to slow climate change.
"We clearly stated our strong objections to the EU plans on both legal and policy grounds," a U.S. administration official told a telephone news conference after talks between EU and U.S. negotiators.
In the strongest public criticism of the EU carbon scheme to date by President Barack Obama's administration, Washington said U.S. airlines should be exempt from greenhouse gas penalties.
The official, who spoke on condition of anonymity like all other delegates, said the EU was using "the wrong way to pursue the right objective" of slowing global warming that is predicted to cause more droughts, floods and rising sea levels.
The European Commission said there were no plans to back down, echoing statements by President Jose Manuel Barroso earlier this month. .
"The Commission is ready to consult at any time, but there should be no illusion -- the EU does not intend to withdraw or amend the ... directive. It is established EU law," an EU official at the meeting told Reuters.
Several U.S. airlines are challenging the EU measure in European courts. Washington said its demands in Oslo focused on an exemption, not to try to get the EU to scrap the scheme.
"The demand we made is that the EU ETS (Emissions Trading Scheme) should not apply to U.S. carriers. We did not talk about how that might be done," another U.S. official said.
Washington has no plans to match the EU move from Jan. 1, 2012, when the EU will require all airlines flying to Europe to be included in the ETS, a system that forces polluters to buy permits for each tonne of carbon dioxide they emit above a certain cap.
China has also strongly opposed the EU plan, saying it will cost Chinese airlines 800 million yuan ($123 million) in the first year and more than triple that by 2020.
U.S. officials declined to speculate about what might happen on Jan. 1, 2012, if the deadlock is unresolved. The EU has said it will impose fines for non-compliance.
The EU is aiming to cut greenhouse gas emissions by 20 percent below 1990 levels by 2020, or by 30 percent if other nations also set tough goals in stalled U.N. negotiations on a U.N. treaty to slow global warming.
Obama wants strong U.S. action to slow climate change but has been unable to persuade the U.S. Senate to pass a law to cut U.S. emissions by 3-4 percent below 1990 levels by 2020.
The officials said Washington was working to cut emissions from aviation, including with a Next Generation Air Transportation System.
Annie Petsonk, of the U.S. Environmental Defense Fund, said the Obama administration had a choice.
"It can stand in the way of the only programme in the world that sets enforceable limits on carbon pollution from aviation, or it can begin to craft a programme that taps the ingenuity of this dynamic sector to cut pollution, lower costs and reduce America's dependence on imported oil," she said.
(Reporting by Alister Doyle; Editing by Janet Lawrence)
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