Progress has been made in the climate talks in Copenhagen but negotiators are still engaged in heated debate on some issues, the head of the Chinese delegation to the UN-led climate talks said on Monday.

Xie Zhenhua, vice minister of the National Development and Reform Commission, told reporters that at the start of the talks, the debate focused on what draft texts should serve as the basis for discussion after some unofficial texts of the draft was leaked.

In the end, the dual-track principle for talks under the Bali Road Map was upheld with the emergency of two draft texts proposed by the chairs of two major working groups of the UN Climate Change Conference, Xie said.

The two texts meet the requirements of the Bali Road Map in format, but "we are not fully satisfied with the texts," he said.

Many of the issues in the texts need further discussion and modification, and the ensuing substantial discussion on the texts would be very hard, given the differences in national interests and understandings of the Kyoto Protocol, he noted.

Many sticking points are yet to be resolved, such as the binding targets of emissions reduction for the United States, which is not a party to the Kyoto Protocol, he said.

Ministers arrived in Copenhagen over the weekend to work for consensus on the texts at a higher level of the two-week talks. More than 100 heads of state and government are expected to be arriving later in the week for a climate summit to endorse efforts to fight global warming.