The United States should do more in cutting greenhouse gas emissions and providing financial and technological support to developing countries, said a World Wildlife Fund for Nature (WWF) official on Thursday.

U.S. President Barack Obama has vowed to cut U.S. emissions by 17 percent from 2005 levels by 2020.

"That target is too small and it needs to be increased," said Kim Carstensen, director of WWF's Global Climate Initiative, in an interview with Xinhua.

He said Obama still needed to convince other countries that he was able to deliver what he had promised although his decision must be approved by the U.S. Senate in the first place. "We do not want empty promises," said Carstensen.

Empty promises have been seen when the United States signed the Kyoto Protocol and then never ratified it. "We cannot have these empty promises again," he said. "We need to be sure that the U.S. promise delivers."

Carstensen said he hoped Obama could make sure that climate change would be the next top priority issue in the U.S. legislature so that it would not get postponed or sidelined.

The United States is facing mounting international pressure to do more on the climate change issue. "We have a better chance than ever. If we miss this chance, we're never going to get a better one," said Carstensen.

He said other developed countries should also raise their emission reduction targets and offer more financial and technological support to developing countries.

Carstensen also said China's target of reducing the intensity of carbon emissions per unit of its GDP in 2020 by 40 to 45 percent against 2005 levels is encouraging and that he was confident that China can reach the goal.

With 110 heads of state or government coming to the UN Climate Change Conference, Carstensen was confident that a framework on climate change could be inked.

"The framework needs to have clear definitions, numbers on emission reductions, numbers for early start funding and further long-term funding," he said.

"We need to continue the Kyoto Protocol and at the same time we need another framework which takes in the United States and its commitments," he said.

The framework also needs to take in a number of issues, including deforestation, adaptation to climate change, technological transfer, financing and concrete actions of both developed and developing countries, Carstensen said.