The European Union and the United States are at loggerheads over climate change and energy policy.
The two powers are due to meet next week to dicscuss economic convergence issues, global warming and energy.
The German Foreign Minister Frank-Walter Steinmeier has said that while the two sides had made progress in preparing for the summit on economic convergence issues, the same could not be said of global warming and energy.
Diplomats said Washington was refusing to make any firm commitment to reducing greenhouse gas emissions blamed for global warming.
They are also refusing to an agreement to curb climate change after the first phase of the Kyoto Protocol expires in 2012.
One diplomat said it was possible there would be no agreed joint delcaration at the 30 April 30 Washington summit.
