The world's top greenhouse gaspolluters, including the United States, have a "special responsibility" to produce fewer emissions, U.S. President George W. Bush said Friday, amid growing international pressurefor the countries toaccept binding targets on reducing emissions.

Bushtold representativesfrom the 16 top polluting countries at a U.S.-sponsoredconferenceon climate changein Washington that they must come together to set a goal for emissions reductions.

"Energy security and climate change are two of the great challenges of our time," Bush said. "By setting this goal, we acknowledge there is a problem, and by setting this goal, we commit ourselves to doing something about it."

He said each nation should establish for itself what"tools" it will use to rein in the pollution problem without stunting economic growth.

"The nations in this room have special responsibility," he said. "We must lead the world to produce fewer greenhouse gas emissions. And we must do it in a way that does not undermine economic growth or prevent nations from delivering greater prosperity for their people."

The conference comes ahead of a United Nations summit in December aimed at crafting an agreement to succeed the emissions-target-based Kyoto Protocol, which Bush rejected in 2001.

Bush said he hoped for a global consensus in the December negotiations in Bali, Indonesia, where he said the U.S. would play an active role in securing a "strong and transparent" way for countries to measure their anti-climate change efforts.

But critics have said they fearthe Bush administrationmight useits ownnegotiations to circumvent the talks and stir up support among other countries for voluntary emissions-reduction targets, instead of Kyoto's binding cuts.

U.S. using Canada as a 'cover': NDP environment critic

The two-day U.S. conference includes representatives from Canada, Australia, Britain, Brazil, China, France, Germany, India, Indonesia, Italy, Japan, South Korea, Mexico, Russia andSouth Africa.

Environment Minister John Baird, whoattended the meeting for Canada, said he supported the U.S. in its effort to get the top polluting countries together and indicated Canada could help broker talks.

"We really need everyone on board— every country with an oar in the water and everyone rowing together— if we're going to win this battle," Baird told CBC News from the Canadian embassy in Washington.

He added that the conferencesaw "very encouraging signals" from China,one of the toppolluters and a country key to any agreement.

Meanwhile, NDP environment critic Nathan Cullen, whowas in Washington to monitor the talks, dismissed the Bush-organized conference as a "photo op."

In an interview with CBC News on Friday, Cullen accused Baird and the Conservatives of allowing the U.S. touse Canada's reputation as "cover" for its own weak climate-change initiatives. "They're cut from the same cloth," Cullen said of Baird and Bush.

"The real shift that we need to see in our economy to help our environment needs to come with binding targets."

U.S. is a 'major emitter': Rice

Under the Kyoto Protocol, which was signed by Canada under the Liberal government in 1998 and ratified in 2002, the country agreed to reduce greenhouse-gas emissions by six per cent from 1990 levels by 2012.

Prime Minister Stephen Harper has repeatedlysaid Canada cannot meet its Kyoto commitments withoutcripplingits economy.Instead, theHarper governmentput forwardits own plan to cut emissions by six per cent below 1990 levels, but not untilsometime after 2020— years beyond the Kyoto deadline to reach the same goal.

On Thursday, U.S. Secretary of State Condoleezza Riceacknowledged her country's role asa "major emitter." She insisted theBush administrationis serious about global warming and making progress to slow its growth rate in carbon dioxide and other industrial warming gases.

"I want to stress that the United States takes climate change very seriously, for we are both a major economy and a major emitter," Rice said. "Climate change is a global problem and we are contributing to it, therefore we are prepared to expand our leadership to address the challenge."

Rice also gave reassurances that the U.S. intent is to contribute to the UN negotiations, even though those emphasize mandatory controls on carbon dioxide that Bush opposes.

Bush rejected the Kyoto accord because he said it unfairly harmed the economies of rich nations like the U.S. and excluded developing nations like China and India from having to cut greenhouse gases.

Yvo de Boer, executive secretary of the United Nations Framework Convention on Climate Change, told the 16 nations participating in the meeting that "this relatively small group of countries holds a key to tackling a big part of the problem."

But he added their response could succeed only by "going well beyond present efforts," especially among rich, industrialized nations.

With files from the Associated Press