Delegates at the United Nations climate conference in Copenhagen began substantive negotiations Tuesday, working toward compromises on greenhouse gas cuts and financial aid for developing nations ahead of a planned gathering of more than 110 world leaders later in the week.

Momentum got a lift when the US Environmental Protection Agency classified six greenhouse gases as dangerous pollutants subject to federal regulation, a move that bypassed Congress and signaled fresh American commitment to the talks. France's climate ambassador called the step a credibility boost for US pledges.

Conference chair Connie Hedegaard plans to survey national positions toward the end of the week and assemble a draft framework, which environment ministers and then heads of state will review. Leaders attending include US President Barack Obama, China's Premier Wen Jiabao, and the heads of all 27 European Union member states.

Any agreement reached would set emissions-reduction targets for major polluters and establish principles for long-term climate finance, potentially worth hundreds of billions of dollars, to help poorer nations adopt cleaner technology. Rich countries face pressure to provide $10 billion a year in fast-start funding from 2010 through 2012. A final accord, if ratified, would take effect in 2013.

Historical summary. TurkishPress restated this wire report, first published in December 2009, in its own words.