Four nations will propose a "green fund" on Wednesday to try to break deadlock on ways to raise and manage billions of dollars at U.N. climate talks in Copenhagen, delegates said.

Britain, Australia, Mexico and Norway would outline ideas in a document for raising billions of dollars towards 2020 at the Dec. 7-18 talks.

"I can confirm that there will be an initiative from these countries, not on the size of the amount but about how we see the structure of finance in a new agreement," said Hanne Bjurstroem, head of the Norwegian delegation.

A British official said the document would look at ideas for a green fund for developing nations, partly to help them adapt to climate changes such as floods, droughts, rising sea levels and species extinctions.

Mexico has in the past suggested that all countries should pay into a fund that would be distributed to the poor. Norway has proposed that some carbon emission allowances could be auctioned off to raise cash for developing nations.

The United Nations estimates that the fight against climate change may cost about $300 billion a year in the long term.

Disputes over who should pay are one of the main causes of friction at the U.N. talks, along with splits about how far developed nations should cut emissions by 2020.