LONDON - The US is refusing to sign a flagship global climate fund as negotiations intensify ahead of the UN climate summit next week, the Financial Times reported on Thursday.

It quoted US officials as saying the United States, backed by Saudi Arabia, had still not agreed to adopt a blueprint for the Green Climate Fund.

Countries agreed to create the fund last year to channel up to $100 billion a year by 2020 to help developing countries fight climate change and a UN committee completed the draft design of the fund at a meeting in South Africa in October.  

Negotiators from around the world will consider the proposals at a climate summit in Durban from Nov 28 to Dec 9, as they try to agree on steps towards a global binding climate deal.

Earlier this month, UN Secretary-General Ban Ki-moon urged governments in rich nations to work around troubled economic times and scale up donations to the fund that he said was at risk of becoming an "empty shell".

The US never ratified the ailing Kyoto Protocol, which aims to reduce the risk of greater extremes of weather, rising sea levels and crop failures. Adopted in 1997, it entered into force in 2005 and subjects 37 richer countries to legally binding targets for cutting greenhouse gas emissions during its 2008-12 first commitment period.

So far the world is failing to reduce carbon emissions sufficiently to contain global warming within the limit of 2 degrees Celsius that scientists say is necessary to avoid the worst effects of climate change.

The US State Department had no immediate comment.