Last year EU states agreed to cut emissions by 2020 and increase the share of wind, solar, hydro and wave power in electricity output by the same date.
Failure to agree on the details by this time next year would delay EU laws and weaken the bloc in United Nations talks on curbing emissions with other countries in Copenhagen in November 2009.
EU leaders are aware that other countries are also preparing their economies for tougher climate change rules to come into force after the first phase of the Kyoto Protocol.
The protocol, which aims to reduce greenhouse gases that cause climate change, ends in 2012.
Speaking to Italy's Il Sole 24 Ore newspaper, Jose Manuel Barroso, the European commission president, said: "The United States has started to invest in eco-technology and in renewables.
"When they decide to do it on a massive scale, it will be hard for Europe to compete, at least if it doesn't decide to step on the accelerator right now."
The leaders will receive a report by Javier Solana, the EU foreign policy chief and Benita Ferrero-Waldner, external relations commissioner, which says that "significant potential conflicts" are likely in years to come because of "intensified competition over access to, and control over, energy resources".
France's plans for a Mediterranean project are likely to prove controversial with Nicolas Sarkozy, France's president, already having had to promise Germany that he would water down a plan he first raised during his election campaign last year.
Ahead of the summit, Jean-Claude Juncker, Luxembourg's prime minister, underlined a concern already voiced by Angela Merkel, Germany's chancellor, that some EU nations might be excluded.
|"What's important is that all the EU member countries take part in an equitable |
way in this undertaking"
Jean-Claude Juncker, Luxembourg's prime minister
"What's important is that all the EU member countries take part in an equitable way in this undertaking," Juncker said.
Backing this view, Barroso said: "We really welcome this, at the same time, it is important that all member states of the EU are engaged in it ... we hope that all countries in the region ... will be participating."
Once seen as a fully-fledged club for Turkey, whose EU membership is opposed by France, the new union appears to have evolved into a forum for co-operation with countries around the Mediterranean rim.
Some EU countries doubt the usefulness of creating a new structure for existing policies and many are also worried about how the project would be financed since a unanimous vote would be required for any EU funds to be used.
Britain and Scandinavian countries are notably sceptical about the project.
Barroso also announced on Thursday that Croatia should be able to complete European Union membership talks in time to join the bloc in 2010.
After meeting Ivo Sanader, the Croation prime minister, he said he had "every confidence" that the talks would be finished by the end of next year.
Croatia still has work to do in reforming its judiciary and public administration record to meet EU standards, Barroso said. But it has passed major hurdles in co-operating with the UN war crimes tribunal and, most recently, by suspending a fishing dispute with Slovenia and Italy.
"If Croatia fulfills its obligations I'm sure all member states will support" the candidacy, he said, adding that the commission would soon give Croatia a timetable for accession talks.
It was the first time an EU official has spoken of a concrete timetable for Croatia.
In Brussels, Sanader said that EU membership was an "absolute national interest" for Croatia.