Countries are still squabbling over how much power a United Nations fund will have to help developing countries tackle climate change, just weeks ahead of a crunch summit in South Africa to work on a global climate deal, an EU negotiator said.

Last year, countries agreed to create the Green Climate Fund to channel up to $100 billion (62 billion pounds) a year by 2020 to help developing countries fight climate change.

Last month, a U.N. committee completed the draft design of the fund at a meeting in South Africa.

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

The United States and Saudi Arabia have raised some objections to aspects of the fund's design, Laurence Graff, head of the international and inter-institutional relations unit at the EU Commission, told reporters.

The nature of these objections -- whether they are serious concerns or (the two countries) wish to add to recommendations -- remains to be seen, Graff said.

The United States and some other nations want the World Bank to have a central role in managing the fund but some developing countries and environmentalists are against, arguing that it does not have the right environmental credentials.

The issue is indeed whether the fund should be allowed to carry out its own projects without resorting to the World Bank, she said.

That is still open (to discussion).

Another related issue has been driven by some rich countries which insist the private sector should be the main source of climate finance, as governments are unable to raise enough public funds in constrained economic conditions.

There are concerns that these rifts could threaten to derail the fund's launch, seen in 2013, and Graff said there was a lot of work to do.

There are a number of issues (related to the fund) to be discussed in Durban, including at ministerial level, Graff said.

Overall, my impression is that the (design) proposals are a good basis for discussion and I am hopeful we will be able to ensure a good outcome.

(Reporting by Nina Chestney)