BRUSSELS--European Union leaders are expected to spar over the bloc's energy and climate-change goals at a summit on Thursday, as some countries are demanding financial concessions in return for committing to the bloc's ambitious targets.

An agreement on a set of goals this week is seen as vital if the EU is to make good on its pledge of setting an example to other nations ahead of next year's United Nations talks in Paris on tackling climate change. Given that other EU-leader meetings this fall are likely to be focused on Europe's moribund economy, Thursday's gathering could be the only chance for leaders to settle on a package in time to help shape the outcome of the U.N. conference.

The EU's 28 leaders are aiming to agree on a trio of targets to be reached by 2030: cutting Europe's greenhouse-gas emissions by 40% below 1990 levels, bolstering its renewable energy sources by 27% from 1990 levels, and improving energy efficiency by 30% compared with 2010.

European diplomats say the targets will have to be agreed upon in one package, as they are mutually dependent. "There's not a single country that doesn't have some problem with these targets," one EU official said. "It's now about taking all those conflicting concerns into account and yet still coming up with something credible at the end of the day."

At least one of the package's main objectives may need to be watered down to ensure a deal this week. Last-minute talks aimed at averting a possible veto by one of the member countries were still in progress late Wednesday and could continue until just before the summit's opening, diplomats said.

This week's meeting comes as the EU is aiming to reduce the bloc's dependence on imports of fossil fuels, particularly from Russia amid heightened tensions with Moscow. The EU paid around EUR140 billion ($177 billion) for Russian oil and gas in 2013, according to the European Commission, and the bloc is currently trying to resolve a gas dispute between Russia and Ukraine to avert shortages this winter.

Advocates of ambitious efficiency targets, including Denmark and Germany, say reducing energy consumption is the simplest way of reducing fuel imports, which cost the bloc EUR1 billion a day, according to the commission.

But the U.K., usually one of the more progressive countries on climate change, has said it won't accept the current efficiency proposal, arguing that the upfront costs of measures such as insulating public buildings would far outweigh the benefits.

One possible compromise could be to reduce the energy efficiency improvement target to 27% from 30%, and to make it just a goal rather than a binding target, EU officials say.

Some negotiators said British Prime Minister David Cameron's opposition to the target is partly fueled by pressure from the euroskeptic U.K. Independence Party, which argues that Brussels" powers should be curbed. UKIP has expressed outrage over recent reports that the EU would regulate household appliances.

"The U.K. has a cost issue, certainly, but this is also all about UKIP and the whole media saga around vacuum cleaners and hair dryers," one diplomat from a Nordic country said.

Meanwhile Poland, which still relies heavily on its coal mines for power generation, has been leading a coalition of Central and Eastern European countries that either oppose the targets or want them to be less demanding.

Officials say Poland and its allies will likely agree upon the package but only in return for financial sweeteners, such as extra EU funding for modernizing their energy infrastructure. Under the EU's so called burden-sharing system, countries with high gross domestic products such as Germany could end up paying for much of any energy upgrades in central and Eastern Europe.Warsaw has also negotiated a bigger share of free allowances under the EU's emissions trading system until 2024, meaning that its power sector would effectively be allowed to continue emitting high levels of carbon dioxide, one diplomat said.

"I really do hope that [EU] leaders will show responsibility and see that nothing gets easier by postponing [these decisions]," Connie Hedegaard, the EU's climate-change chief, said. "We know where the problems are, and we know more or less where the landing zones can be. It's about getting it done."

The EU's energy targets have divided businesses. More energy-intensive sectors, such as steel and chemicals producers, warn the measures could drive up energy prices that are already rising higher than in rival economies such as the U.S.

But a coalition of 25 global companies, including Royal Dutch Shell PLC, Unilever PLC and Coca-Cola Enterprises, this week supported the package in an open letter to EU leaders. "Our politicians must show leadership," said Paul Polman, Unilever's chief executive. "Without the right policy frameworks and political signals, even the most determined business action will not reach the scale we need to make a real difference."

Discussions are also likely to be held at the summit on better integrating Europe's energy infrastructure. Spain and Portugal are leading the push as they say they are unable to sell on their excess energy supply because of weak interconnection between their power grids and the rest of Europe.

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