* U.N. chief fears crisis sapping "political will" on aid
* Ban will urge G20 summit to keep pledges to poor
* Ban heartened by Obama's "proactive" climate policy
By Sean Maguire and Patrick Worsnip
UNITED NATIONS, March 20 (Reuters) - U.N. chief Ban Ki-moon said he would press world leaders at a financial summit next month to keep their pledges of aid to poor nations, but expressed concern the global crisis would sap their resolve.
In an interview with Reuters on Thursday, the U.N. secretary-general said that although he had been encouraged by the promises from wealthy countries not to reduce their development assistance, he was worried that might not last.
"As the situation is deteriorating ... I am concerned that this may inevitably affect the political will and available resources for the developing countries," he said. "My role ... is to keep world leaders on their committed path."
Ban said he would not accept any delay to agreed targets for sharply improving life for the world's poor, despite a suggestion by at least one prominent U.N. adviser that the Millennium Development Goals may not be met in time.
The eight MDGs, announced in 2000, set targets for slashing poverty, hunger and disease by 2015. Most of them were behind schedule even before the financial crisis set in last year. Economist Jeffrey Sachs, who advises Ban, said in Tanzania last week the date might have to be pushed back.
Ban said: "We cannot move this target date. 2015 is the deadline and target. We must be able to keep the target."
He said he would write to all heads of state and government attending the Group of 20 summit in London on April 2 to urge them to not to lose sight of the plight of the poor as they seek ways out of the financial crisis.
"That will be my strong message to the leaders of the G20," said the U.N. chief, who will be at the summit that brings together the world's top economies and major developing nations such as India and Brazil.
GREEN GROWTH
Ban said he was heartened by pledges by U.S. President Barack Obama and British Prime Minister Gordon Brown to protect poorer nations and promote ecologically viable "green growth," which Ban sees as one way out of the financial crisis.
"I am encouraged by President Obama's very engaging and proactive policy on climate change, unlike the previous administration. This is very important," he said.
Obama has made combating climate change a major plank of his policy. His predecessor, George W. Bush, refused to ratify the existing Kyoto Protocol on emissions targets, saying it would put the United States at an economic disadvantage.
Ban, who met Obama in Washington last week, said he understood the Obama administration would try to convene next month a Major Economies Meeting, or MEM, grouping 16 nations that account for most of the world's greenhouse gas emissions.
"The biggest emitter countries will get together, including China and India. They will have to agree on their emission targets. That will help and will be very much complementary to ongoing (U.N.) negotiations," he said.
White House officials could not immediately be reached for comment.
Ban, who also met members of Congress during his Washington visit, said he urged them to pass legislation to commit the United States to the battle against climate change.
"The whole world is looking to the American leadership, and I am reasonably encouraged by what the United States is going to do," Ban said.
A series of U.N.-led meetings this year will culminate in a two-week gathering in Copenhagen in December that is intended to produce a successor to Kyoto and set goals for the substantial reduction of emissions in future.
Ban stopped short of saying he was certain Copenhagen would achieve its task, but said, "That's my goal, my target and I'm working very hard." (Editing by Peter Cooney)