The United Nations has conceded that a deal in Copenhagen on climate change might not include promised financial aid for developing countries, an admission that will infuriate poorer nations and potentially scupper a broad-based agreement.

Ban Ki-moon, secretary- general of the UN, told the Financial Times in an interview that countries could sign a deal at Copenhagen without a firm commitment from developed nations on long-term financing for poorer countries to combat global warming. “We can start next year discussing this matter,” Mr Ban said. Developing countries have long insisted that any Copenhagen deal must include assurances that they would receive finance flows of at least $100bn a year by 2020.

“I'm not quite sure [we can get a long-term financing number] . . . I don't think the exact number itself should be all of this Copenhagen deal. There are many important issues,” he said. “If they are not able to agree this time at Copenhagen, then there needs to be some initial arrangement [on financing].”