Brussels (AFP) - European Union leaders agreed Friday what they hailed as the world's most ambitious climate change targets for 2030, paving the way for a new UN-backed global treaty next year.

The 28 leaders overcame deep divisions at a summit in Brussels to reach a deal including a commitment to cut greenhouse gas emissions by at least 40 percent compared to 1990 levels.

They also agreed on 27 percent targets for renewable energy supply and efficiency gains, in spite of reservations from some member states about the cost of the measures.

"Deal! At least 40 percent emissions cut by 2030. World's most ambitious, cost-effective, fair EU 2030 climate energy policy agreed," EU president Herman Van Rompuy tweeted.

The EU wanted to agree on the targets ahead of a summit in Paris in November and December 2015, where it is hoped the world will agree to a new phase of the Kyoto climate accords which run until 2020.

The agreement puts the EU "in the driving seat" ahead of the Paris conference, European Commission head Jose Manuel Barroso said.

Environmental groups complained that the deal did not go far enough to cut global warming.

- Late-night talks -

The European leaders haggled late into the night amid a split between richer, greener nations and poorer countries that depend heavily on fossil fuels or on gas from Russia.

Poland had previously threatened to veto a deal, fearing that its near complete reliance on coal would have made it prohibitively expensive to meet the targets.

German Chancellor Angela Merkel and French President Francois Hollande had talks with Polish premier Eva Kovacsz on the sidelines of the summit in a bid to talk her round.

Merkel, whose country is a leader in renewables, said the deal would "give Europe a voice and a negotiation position in the international climate talks."

The accord also promotes new interconnection links between member states allowing them to export up to 15 percent of their power output when they are in surplus and import up to 15 percent when they are in deficit.

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Van Rompuy said these interconnection links were a key part of developing the EU's energy market and would provide insurance against supply disruption.

Van Rompuy cited both the Ukraine crisis and turmoil in the Middle East as good reason for the EU to act now to bolster its energy security.

- Builds on 2020 targets -

The climate deal builds on the EU's targets for 2020 of a 20 percent cut in greenhouse gases, blamed for global warming, a 20 percent boost in renewables such as solar and wind power and a 20 increase in energy efficiency.

While the new 40 percent target for greenhouse gases and 27 percent for renewables agreed Friday were as expected, a 30 percent goal for an increase in energy efficiency set in July by the Commission was watered down to 27 percent.

Environment group Greenpeace said the EU had "pulled the handbrake on clean energy".

"These targets are too low, slowing down efforts to boost renewable energy and keeping Europe hooked on polluting and expensive fuel," it said

British-based humanitarian group Oxfam called for targets of 55 percent in emissions cuts, 40 percent for energy savings and 45 percent for renewables.

The EU meanwhile named Christos Stylianides of Cyprus as the bloc's coordinator to fight the Ebola disease which has claimed nearly 4,900 lives in west Africa.

Stylianides is the incoming EU commissioner for humanitarian aid.

British Prime Minister David Cameron said that other EU nations "need to do more" than the nearly 600 million euros ($750 million) they have currently pledged to fight the virus.

The leaders were set to discuss the Ukraine crisis although any progress is unlikely as an EU review on the ceasefire between Kiev and pro-Moscow rebels is not due until next Tuesday.

They will search for ways on Friday to foster economic growth and jobs amid fears of a triple-dip recession.