BEIJING (Reuters) - China is glad a climate change roadmap agreed last week in Bali has drawn the United States to the negotiating table, but the world's only superpower must do more to tackle global warming, a top official said on Thursday.

China says rich nations should bear much of the burden for tackling global warming in the short term because of their historic responsibility for causing the problem.

Developing nations want more help with technology and cash for adapting to a warmer world and Yu said the poorest countries, still struggling to feed their people, could not be expected to pay for expensive emissions-cutting technology.

"The United States is an important contributor of emissions both in total and on a per-capita basis. It has both advanced technology and ample funds," he told a briefing.

"So on the issue of tackling climate change, America should display a more positive, more constructive role."