Russian President Dmitry Medvedev added his diplomatic weight to an impromptu summit of world leaders on the sidelines of United Nations talks in Copenhagen on Friday, diplomatic sources said.
Medvedev's arrival meant that all five of the United Nations Security Council's permanent members had joined the talks, together with all five of the Group of Five (G5) leading developing economies and all but two of the Group of Eight (G8) developed economies, dpa reported.
The talks were meant to forge consensus between the world's major power blocs on how to fight global warming ahead of a crunch meeting of some 120 heads of state and government on Friday.
The leaders of Britain, France, Germany, Japan, Brazil, Mexico and South Africa all joined the talks in person, diplomats said. The US was represented by Secretary of State Hillary Rodham Clinton, while India was represented by Environment Minister Jairam Ramesh.
China was represented by senior officials, diplomats close to the talks said, contradicting earlier reports that premier Wen Jiabao had chosen to come in person.
The mini-summit was suggested by Swedish Prime Minister Fredrik Reinfeldt, current holder of the EU's rotating presidency, and Jose Manuel Barroso, head of the European Commission, who also attended.
Their aim was to "help build a consensus for a global deal that produces an ambitious outcome to this conference" ahead of final talks on Friday, an EU statement said.