COPENHAGEN (Reuters) - A draft U.S. climate bill did not go far enough to cut greenhouse gases, U.N. Secretary-General Ban Ki-moon told Reuters on Sunday, three days after the plan won a key Congressional panel vote.

Ban applauded President Barack Obama’s engagement on global warming but said that other countries were doing more, and added that a new global climate pact meant to be agreed in December could not wait for the United States to pass its domestic rules.

“That’s what I have been doing and will continue to do,” Ban said when asked if he was urging the United States to do more.

The bill passed on Thursday aimed to cut U.S. greenhouse gases that contribute to global warming by 17 percent below 2005 levels by the year 2020.

“That’s clearly lower than other countries are now aiming, particularly the European Union,” Ban said on the fringes of a climate change and business conference in Copenhagen.

“I appreciate President Obama and his administration taking an active role. Now we need to continue to encourage the United States to do more,” he said, adding that he welcomed the vote by the House of Representatives Energy and Commerce Committee.

The panel’s approval moved the draft bill closer to a vote in the full House, which could occur by August. But it is unclear whether it would go through the Senate by December.

“That should not be any conditionality of this global deal in Copenhagen,” said Ban, who earlier told reporters that a deal in December “was not an option.”

A U.N. General Assembly summit on climate change in September would be the largest forum on the issue and “critically important” to allow leaders to resolve their differences three months before an anticipated deal, he said.

“We will be in a much better position to identify the key sticking points, to sort out at the leaders level. “

“I will try to make this the most interactive debate forum among the leaders so they can exercise ... the commitment and vision to look for the future of the entire planet Earth.”

BLAME

Poorer countries say that the developed world has got rich from more than two centuries of industrialization, spewing carbon dioxide into the atmosphere from burning fossil fuels like coal and oil, and so expect the North to act first.

Developing countries led by China and India want rich countries to cut greenhouse gas emissions by 25-40 percent by 2020 compared with 1990 levels. The goal of the draft U.S. bill is equivalent to roughly no change on 1990 levels.

The United States will try to persuade rich and poor countries to share the burden of fighting climate change this week, holding May 25-26 talks among major economies, including China, the European Union, Russia, India and Japan, in Paris.

Ban identified key challenges to a climate deal in December, and firstly “ambitious targets as scientists tell and as the IPCC (U.N. climate panel) recommends” for developed countries.

Other key objectives included more clarity on funds to help least developed and small island and land-locked developing nations prepare for climate change.