Bilateral talks between US President Barack Obama and Chinese Premier Wen Jiabao have moved a "step forward" toward a possible climate deal, a US official said.
Both leaders directed their negotiators to work further on a deal after meeting for nearly an hour at the UN climate conference in Copenhagen.
Obama and Wen discussed greenhouse gas emission targets, financing for climate aid and transparency in monitoring nations' pledges to cut emissions.
China has been criticised during the summit for not offering stronger carbon emissions targets and for resisting international monitoring of its actions. The US has been criticised for making its climate aid offer so late in the talks.