President Barack Obama said disenchantment over the Copenhagen climate talks was "justified" but defended the chaotic outcome as the top UN envoy urged an end to post-summit recriminations.

The climate change conference held in the Danish capital ended last week with a non-binding agreement that the European Union has blasted as a Sino-US stitch-up which will do little to curtail global warming.

"I think that people are justified in being disappointed about the outcome in Copenhagen," Obama told PBS television Wednesday after the summit ended with only vague prescriptions to curb greenhouse gas emissions.

"The science says that we've got to significantly reduce emissions over the next 40 years. There's nothing in the Copenhagen agreement that ensures that that happens," he acknowledged.

But Obama added: "What I said was essentially that rather than see a complete collapse in Copenhagen... at least we kind of held ground and there wasn't too much backsliding from where we were."

Sweden, which holds the EU's rotating presidency, this week called the summit a "disaster" and declared both China and the United States, the world's two biggest polluters, responsible for the result.

Exposing the stark divide between rich and developing nations, Britain and China have traded verbal blows over who was to blame for the Copenhagen outcome.

Brazil has blasted Obama, while India has congratulated itself for emerging from the summit without any constraints on its booming growth.

Yvo de Boer, executive secretary of the UN Framework Convention on Climate Change, said "all this finger-pointing and recrimination" could cloud fresh attempts next year for sealing a post-2012 pact on tackling global warming.

"We need to work together constructively, whereas countries are in the media blaming each other for what happened -- the same countries that are going to have to be back at the negotiating table next year with an open willingness to work together," he told AFP.

"It's bad for the atmosphere, it's bad for the relationship among people that ultimately have a common goal to move this forward."

In frenzied backroom haggling on Friday, leaders of some two dozen countries put together a "Copenhagen Accord" that strived to save the gruelling 12-day UN marathon from collapse.

A total of 30 billion dollars was pledged from 2010-2012 to help poor countries in the firing line of climate change, and rich nations sketched a target of providing 100 billion dollars annually by 2020.

The deal set the aim of limiting warming to two degrees Celsius (3.6 degrees Fahrenheit), but did not set binding targets to reduce the emissions of gases that scientists say are heating up the world's atmosphere to dangerous levels.

Obama, who traveled to the summit in its final days to push for a comprehensive agreement, said the limited agreement was hard to win, and came after talks nearly broke down entirely.

"The prime minister of India was heading to the airport and the Chinese representatives were essentially skipping negotiations," he said.

"Everybody's screaming," but eventually, "cooler heads prevailed."

In her annual Christmas broadcast, Queen Elizabeth II was to urge the 54 Commonwealth nations to keep taking the lead on global issues such as the environment.

"It is important to keep discussing issues that concern us all -- there can be no more valuable role for our family of nations," Britain's monarch and the head of the Commonwealth will say, according to extracts released Thursday.

De Boer said that going forward, it might be useful for a principal group of countries to propose a climate deal. But time was needed to have it debated and endorsed in a process "that is inclusive, representative and transparent".