Disagreement over a European scheme to tax airlines for carbon emissions may affect talks seeking new global warming targets, US climate envoy Todd Stern said on Tuesday.

"I think that there is a potential for a negative spillover from the ETS on broader climate negotiations," he told journalists by telephone from Rome after a gathering of climate officials of 17 developed and developing countries.

ETS refers to the European Union's emissions trading system, under which a carbon levy was imposed on air travel with effect from January 1.

India's environment minister said last week the tax was a "deal breaker" ahead of global climate change talks later this year.

The 27-nation EU has said the tax will help it achieve its goal of cutting emissions by 20 percent by 2020 and has vowed not to back down.

"I think that there is a risk that there will be some spillover effect if the ETS issue isn't resolved," said Stern.

"I am not predicting that it will or it won't, but I think it has that potential."

Stern said some countries at Tuesday's meeting expressed disapproval of the "unilateral trade steps" taken.

"There are quite a few countries, and I am not even talking about the US right now, who are quite upset about the ETS and upset about what in their judgement it says about the multilateral system and disregard for that system."

The next round of talks under the United Nations Framework Convention on Climate Change (UNFCCC) are to be held in Bonn, Germany next month, leading up to a big meeting in Doha, Qatar from November 26 to December 7.

The Doha gathering will be tasked with elaborating on a roadmap agreed in Durban in December last year towards an accord to bring all major greenhouse-gas emitters under a single legal roof.