European Union leaders committed last week to a target of reducing EU greenhouse gas emissions by 20 percent by 2020 and offered to go to 30 percent if major nations such as the United States, Russia, China and India follow suit.

Making a deal in 2009 would give time for ratification the following year and for such a new emissions scheme to enter force in 2012, Piebalgs said.

It would also be after US President George W. Bush, who refused to ratify the Kyoto Protocol on climate change after he took office in 2001, leaves the White House.

Environmental group WWF expects more countries to join the EU's emissions-cutting plan.

"I am sure other countries will follow suit," senior WWF official Stephan Singer told the summit, with Norway, Japan and Switzerland likely examples.

The United States would also step up efforts to cut emissions once a new president was in place, Singer added.

Piebalgs reiterated that nuclear energy policy was a matter for national governments to decide.

Nuclear energy helps to combat climate change, offers security of supply and would act as a bridge until more renewable energy was on tap, said Utz Claassen, chief executive of German utility EnBW.

Germany has plans to phase out nuclear energy by the early 2020s, a step that would "ignore the fact that a premature exit from existing power plans would add 150 million tonnes a year of CO2", Claassen said.

Piebalgs, who received a mandate from EU leaders to draw up new binding rules on renewable energy targets, said he expected a "green light" from the European Parliament soon to draft binding measures.

Earlier this week in the EU assembly the Green Party said it was sceptical about how targets on renewables would be enforced.

Piebalgs said the measures would be in the form of a directive enforceable in the usual way, with legal action possible against those who fail to comply.