By Alister Doyle and Nina Chestney

OSLO/LONDON (Reuters) - Rich nations are dismaying developing countries with pledges merely to continue aid to help them combat climate change in 2013 despite past promises of a tenfold surge to $100 billion a year by 2020.

"There should be a transparent process to scale up finance" towards 2020, said Seyni Nafo of Mali, spokesman for the 54-nation African group at U.N. negotiations. The poor needed more than "an indication that funding will not fall off a cliff".

A looming gap in aid pledges after a 2010-12 "fast start" program of $10 billion a year is a big source of tension before U.N. talks in Qatar from November 26-December 7 meant to review progress towards a deal to fight global warming, due by 2015.

The problem dates back to a U.N. summit in Copenhagen in 2009, when leaders including President Barack Obama agreed the fast start program and set a separate goal of $100 billion in annual aid by 2020 to help the poor to slow global warming.

But no one spelled out what would happen from 2013-19.

Now, with many donors struggling with economic crises, there is little spare cash for climate aid, funds meant to help poor nations to curb rising greenhouse gas emissions and adapt to droughts, floods, heatwaves or rising sea levels.

Major donors -- the European Union, the United States and Japan -- are only giving reassurances about continued aid for 2013, without firm numbers. And they are putting off any surge.

"Finance is key to agreeing on a package at Doha," said Pa Ousman Jarju of Gambia, chair of the 48-nation group of least developed countries. He expressed hopes for "renewed U.S. action on climate change" after Obama's re-election.

Small island states want "scaled-up, new and additional, predictable and adequate climate finance" from 2013, said Samoa's ambassador to the U.N., Aliioaiga Feturi Elisaia.

GREEN FUND

Developing countries want at least new cash for a fledgling, still-empty U.N. Green Climate Fund that is meant to channel aid towards developing nations.

Christiana Figueres, the head of the U.N. Climate Change Secretariat, said that aid would not fall.

"Governments ... will at least maintain the current funding and they will in Doha look at the path along which they will ramp up to reach the $100 billion of mixed-sources of funding," she told Reuters in Singapore.

Some analysts are not so sure.

"At the very best we are looking at a flat-lining but we fear we will see a fall compared to the fast start finance," said Tim Gore of development group Oxfam. He said Spain, Italy, Greece and eastern Europe would all cut.

Under the U.N. plan, all nations will agree by 2015 a deal to slow climate change that will enter into force by 2020. China, the United States, the EU, India and Russia are the top emitters of greenhouse gases. Continued...