Europe and the United States are set to launch trade talks early next year to deepen the world's largest trading relationship, EU and US officials say, potentially unleashing billions of dollars of new transatlantic business.

Together, the bloc and the United States account for about half the world's economic output and nearly a third of world trade. But a debt crisis in Europe and elusive American growth are pushing both sides to consider knocking down the final barriers to trade.

A deal could increase economic output by $158 billion a year for Europe alone and add 0.52 percent to the EU's GDP in the long term, according to European Commission estimates, benefiting industries ranging from chemicals to automakers.

An expert group co-chaired by EU Trade Commissioner Karel De Gucht and US Trade Representative Ron Kirk will in December issue a report recommending pursuing talks, EU and US officials say. They do not expect the outcome of the US Nov 6 presidential election to influence discussions, though the campaign limits their ability to speak publicly about it.

"The report will recommend the negotiation of a comprehensive agreement between the US and the EU," said a senior EU official who declined to be named.

"Talks could begin in the spring," a second official said.

EU leaders at a two-day summit in Brussels from Thursday will also commit to "working toward the goal of launching in 2013 negotiations on a comprehensive transatlantic trade and investment agreement", according to draft summit conclusions.

US officials in Washington said that talks would go ahead, but that there would be no announcement until after the election. EU-US commercial links are unrivalled. Transatlantic trade in goods and services is worth $700 billion a year.

Total US annual investment in the European Union is higher than in all of Asia, while EU investment in the US far outstrips EU investment in India and China combined.

A deal would be the most ambitious in a new generation of sophisticated agreements that go beyond tariffs to take in intellectual property rights, services and regulation.

Eliminating barriers in the automotive sector, which makes up the largest chunk of EU-US trade, could bring a 15 percent fall in costs for both sides, the Commission estimates.

"It would be very useful for us," said Sergio Marchionne, chief executive of Fiat and Chrysler, during a visit to Brussels last week, adding that the deal could make it easier to exchange car components across the Atlantic.