Brussels - The European Union is set to sidestep a bitter internal fight on how to pay developing countries to fight climate change at a summit in Brussels next week, according to internal documents seen by the German Press Agency dpa.

"All countries, except the least developed, should contribute to the financing of the fight against climate change in developing countries ... The main principles of contribution should be the ability to pay and the responsibility for emissions," a draft statement prepared for the June 18-19 summit reads.

Nonetheless, "this is without prejudice to the internal EU burden sharing, which will be determined in good time" before a key United Nations conference on climate change in Copenhagen in December, it says.

The draft statement follows an agreement between EU finance ministers in Luxembourg on Tuesday to call for a common "key" setting out how much major polluters, such as the EU and the United States, should pay developing countries to help reduce their greenhouse gas emissions.

But the ministers also agreed to postpone any debate on how the EU - which would be expected to sign up to a joint funding commitment in Copenhagen - should split the bill among its 27 members.

That debate is expected to be heated, as it potentially covers a bill running to tens of billions of euros.

EU diplomats said that Denmark is leading a push for EU members to use the same key as international states, but Poland wants the bill to be split according to economic performance alone - a key which would greatly reduce its own contribution.

EU officials estimate that the fight against climate change could cost roughly 100 billion euros (139.5 billion euros) per year up to 2020.(dpa)