The United States and Europe are working together to tackle global warming, the chief U.S. climate negotiator said Wednesday, deflecting growing criticism within the EU and the developing world over Washington's perceived go-it-alone stance.

Harlan Watson, leading the U.S. delegation to this week's U.N. climate talks in Vienna, said Washington remains deeply committed despite its refusal to ratify the 1997 Kyoto Protocol.

The U.S. position has angered many in the European Union, which has adopted new targets to cut greenhouse gas emissions that go beyond its Kyoto commitments.

"Certainly we've disagreed with respect to Kyoto, but I'd point out the areas of cooperation," Watson said. "There are probably more areas of agreement than disagreement on this."

The U.S. — which along with China leads the world in emitting carbon dioxide and other gases that scientists say are warming the planet — has called for a Sept. 27-28 conference in Washington of the 15 biggest polluters.

Watson said the Bush administration was "committed to collaborating with major economies" on a new global agreement to cut emissions after Kyoto expires in 2012, and that it would host a series of meetings next year to nudge the process along.

Kyoto requires 35 industrial nations to cut their global-warming emissions 5 percent below 1990 levels by 2012. The EU has pledged to slash emissions by 20 percent by 2020, and by another 10 percent if other industrialized countries join.

"Europe clearly has made a commitment. I would love to see that from the United States," said Hans Verolme, climate change director for the environmental group WWF International.

The Bush administration contends emission caps would damage the energy-intensive U.S. economy, and says it has devoted $29 billion over five years to research on climate and on clean-energy technology.

But Watson played down the rift between the 27-nation EU and the U.S.

"I don't see 'one size fits all' on this," he said. "We've both recognized the importance of a global effort. ... I think we're coming closer and closer to understanding each other."

The U.S. and the EU have been working together on carbon-capturing technology and other measures, he added.

David Doniger, climate policy director for the Washington-based Natural Resources Defense Council, accused the Bush administration of putting too much emphasis on "totally voluntary measures and warm and fuzzy goals that don't achieve anything."

"You've got to approach combating global warming as a business. Everyone in the U.S. gets this now except the administration," he said.

More than 1,000 negotiators and climate experts have been laying the groundwork in Vienna for a major climate summit to be held in December in Bali, Indonesia.

U.N. Secretary-General Ban Ki-moon has called for a broader conference in New York on Sept. 24, three days before the Washington session.