Tariffs aimed at blocking imports from countries which do not have adequate climate-protection laws could spark a trade war, the European Union's designated trade commissioner warned Tuesday, DPA reported.

A number of EU states have called for such tariffs to be introduced following United Nations climate change talks in Copenhagen in December. The talks ended in an agreement which has been widely derided in Europe as a failure.

"There is a big risk that there will be a slippage into a trade war" if such tariffs are introduced, Karel De Gucht told his confirmation hearing in the European Parliament.

Rather than setting up new trade barriers, the EU should develop a "firm political approach which fits in with market laws," De Gucht said, stressing the importance of making any measures compatible with the rules of the World Trade Organization.

The EU has already promised to cut its greenhouse-gas emissions to 20 per cent below 1990 levels by 2020 in a bid to help limit global warming.

But some EU states, with France notable among them, say that the policy could end up forcing European manufacturers to move overseas unless the rest of the world signs up to similar policies.

They have therefore called for "border adjustment mechanisms" which would make imported goods from countries without EU-approved climate laws more expensive.

The EU's trade commissioner is responsible for carrying out trade negotiations on behalf of the 27-member bloc. De Gucht has been nominated to fill the post for the next five years, but his appointment requires the parliament's approval.