* EU to honour pledge to poor nations - environment chief

* Rich regions must clarify ambitions, he says

* Concern over progress at climate talks in Copenhagen

BRUSSELS, March 20 (Reuters) - The European Union will surmount internal disputes and honour pledges to help poor states tackle climate change, the bloc's environment chief said on Friday, urging other rich regions to make clear their goals.

The call by Environment Commissioner Stavros Dimas echoed a warning this week by United Nations climate chief Yvo de Boer, who expressed concern over the slow progress being made before climate talks in Copenhagen in December.

Success at the meeting hinges on whether rich nations can agree a fund worth tens of billions of dollars annually to persuade poor countries to tackle the problem.

The EU promised to do its fair share, but Dimas told Reuters that it could move no further until other rich nations spell out their targets for cutting global warming gases.

"It is obvious that in order to calculate the amount of funding for our contribution, we need to know what other developed countries will do," Dimas said in an interview.

"Japan has announced they will come up with a number in June. I hope it will be earlier. In the United States there is still a shaping-up of policy," he said.

U.S. President Barack Obama will visit Europe in early April and EU officials hope the trip could yield insight on his plans.

The EU aims to lead the battle against climate change after last year agreeing to cut carbon emissions by about 20 percent by 2020 -- the world's most ambitious target so far.

But Poland said on Friday it had won "full influence" on any EU funding plan, suggesting it had the right to veto if it looked too costly in a climate of economic and financial crisis.

However EU leaders in Brussels stood by their commitment to help poor countries cut emissions and to adapt: "The European Union will take on its fair share of financing such actions in developing countries," they said in a final statement.

Developing nations blame industrialised regions like Europe for climate change and say they need financial help adapting to its impact, with investments in drought- or flood-resistant crops, or helping build barriers to rising sea levels.

Polish Prime Minister Donald Tusk said informal discussions had so far focused on an annual EU contribution of between 20 billion euros and 40 billion to developing nations by 2020, and Dimas said that estimate was not far off the mark.

The EU will decide by late 2009 how member states will carve up the financial burden amongst themselves, said Polish European Affairs Minister Mikolaj Dowgielewicz.

"Poland will have full influence on the Union's decisions," he added, suggesting Warsaw had negotiated veto powers.

But Dimas said the concerns of Europe's poorer states would be addressed just as they were during tough EU negotiations last year to clinch a deal on the emission-cutting target.

"We are going to find a solution," he said. "We will be guided by the principle that whatever we do is equitable and fair for all countries."

But he said Europe would struggle to make any further progress on agreeing funding for the developing world without other rich nations revealing their mid-term emissions targets.

"We do move ahead of everybody else... but we expect opinions and ideas from other countries -- the earlier they do so the better," he said. (Editing by Mark John)