Total emissions by 40 leading industrial nations edged up to 18.2 billion tonnes in 2005 from 18.1 billion in 2004 and were just 2.8 percent below a record 18.7 billion in 1990, according to the U.N. Climate Change Secretariat in Bonn.

The 2005 rise confirmed an upwards trend in recent years despite efforts at cuts by many governments worried that climate change, widely blamed on fossil fuel use, will spur ever more floods, droughts, heatwaves and rising seas.

"Since 2000, greenhouse gas emissions...increased by 2.6 percent," the Secretariat said.

Emissions by the United States, long the world's top emitter but with China drawing neck and neck, rose to 7.24 billion tonnes in 2005 from 7.19 billion in 2004, according to the first U.N. compilation of national data for 2005.

Washington has since issued a preliminary estimate that emissions of carbon dioxide, the main greenhouse gas, fell by 1.3 percent in 2006 from 2005 despite robust economic growth.

Revived economic growth in former East bloc nations was a main spur to the overall rise in emissions. Russian emissions rose to 2.l3 billion tonnes in 2005 from 2.09 billion in 2004.