Major economies made progress in defining the building blocks of a new U.N. deal to fight climate change in talks in Paris on Friday but with splits about whether to set a goal of halving greenhouse gas emissions by 2050.

Washington said the talks, among 17 nations accounting for 80 percent of world greenhouse gas emissions, found common ground on sharing clean technologies, financing and possible sectoral emissions goals for industries such as steel or cement.

"In my view we have made significant progress," said Daniel Price, U.S. Deputy National Security Advisor for International Economic Affairs, told reporters on the second of two days of talks including China, Russia, India and the European Union.

But delegates at the meeting, the third of a U.S.-backed series, said that there were deep divisions about whether to set a goal of halving global emissions by 2050, favoured by the European Union, Japan and Canada.

A plan by President George W. Bush to halt the growth of U.S. emissions only in 2025 - long after most industrialised nations who are seeking cuts from a 1990 benchmark under the U.N.'s Kyoto Protocol - made such goals far harder.

The 2050 targets would be considered at a Group of Eight summit in Japan from July 7-9 and at another meeting of the 17 major emitters planned for the sidelines of the summit.

"I think there is a chance we will have it (a 50 percent target) in the declaration" in July, said Andrej Kranjc, Secretary of the Environment Ministry of Slovenia, which holds the rotating EU presidency.

He said the new U.S. goal meant that common 2020 targets - even more relevant to today's policymakers than a 2050 goal - were getting far harder as part of a fight against warming that may bring more floods, droughts, rising seas and heat waves.

DEEP CUTS

Industrialised nations apart from the United States have agreed to consider cuts in emissions of 25 to 40 percent below 1990 levels by 2020 as part of a new U.N. climate treaty due to be agreed by the end of 2009 to succeed Kyoto.

The United States said it was still "seriously considering" a goal of halving world emissions by 2050 even though its own emissions, mainly from burning fossil fuels, would peak in 2025 under Bush's plan. Bush will leave office in January 2009.

U.S. emissions could plunge once new technologies, such as clean coal-fired plants, new biofuels and nuclear power plants came on line in coming decades, said James Connaughton, Chairman of the White House Council on Environmental Quality.

Delegates said many G8 nations favoured setting a 50 percent cut by 205 at the G8 summit. But the United States wanted to agree only if big developing nations were also willing to sign up. Developing nations say rich countries should take the lead.

Earlier, French President Nicolas Sarkozy called on all major economies to act faster to fight global warming, saying new scientific evidence was confirming the "most gloomy scenarios".

"I would like to pass on a simple message to you: the situation is urgent and this urgency must prompt each of us to overcome our defensive reactions, no matter how legitimate they may be," he told the Paris talks.

"Bad news continues to emerge. Scientific models and empirical observations indicate that the events unfolding now confirm the experts' most gloomy scenarios," he said, pointing to a fast melt of polar ice.

The Paris talks group the United States, France, Germany, Italy, Britain, Japan, China, Canada, India, Brazil, South Korea, Mexico, Russia, Australia, Indonesia and South Africa. The European Commission, current EU president Slovenia and the United Nations are also attending.