The European Union and the United States on Monday launched long-awaited formal negotiations to create what would be the world's biggest ever free trade area.
US President Barack Obama said the first round of negotiations on a pact aimed at creating jobs and boosting the fragile global economy would take place in Washington next month.
Speaking just before the start of the G8 summit in Lough Erne, Northern Ireland, British Prime Minister David Cameron said: "We are talking about what could be the biggest bilateral deal in history.
"This is a once-in-a-generation prize and we are determined to seize it."
The process is expected to take up to two years, an ambitious target for such complex international talks.
Obama said the deal "will support hundreds of thousands of jobs on both sides of the ocean".
"There are going to be sensitivities on both sides... but if we can look beyond the narrow concerns to stay focused on the big picture... I'm hopeful we can achieve (a deal)."
The US president said reaching an agreement "will be a priority of mine and my administration".
If a Free Trade Agreement (FTA) can be reached it would be the world's largest: trade in goods between the United States and the 27-country EU last year was worth some 500 billion euros ($670 billion), with another 280 billion euros in services and trillions in investment flows.
The EU says establishing a Free Trade Agreement would add about 119 billion euros annually to the EU economy, and 95 billion euros for the United States.
The head of the EU executive, Jose Manuel Barroso, speaking at the same news conference, said a deal could create "huge economic benefits".
"These negotiations will not always be easy but I am sure they will be worth it," Barroso said. "The current economic climate requires us to join forces and to do more with less."
Barroso said they would "move fast" to seal the deal.
Negotiations will start despite a hard line by France to protect its cherished film and culture sectors from Hollywood, which is seen as potentially offering a bargaining chip to the US side.
A compromise was struck in tense talks in Luxembourg only on Friday.
France insisted that the audiovisual sector be excluded from the negotiations and after 13 hours of talks, a compromise was reached agreeing to Paris' demand while stating that the European Commission could come back on the question if necessary.
Barroso had earlier weighed in with an unusually outspoken criticism of France for its "reactionary" behaviour to defend its audiovisual and cultural industry.
French President Francois Hollande reacted spikily to Barroso's words.
"I do not want to believe that the president of the European Commission could have made these statements on France," he told reporters.
France jealously guards its cultural sector: French television stations are required to air at least 40 percent home-produced content, with another 20 percent coming from Europe before American TV soap operas even get a look in.
Cinema-goers pay a levy on each ticket to help fund the French film industry, which many believe could not survive without such support in the face of Hollywood's dominance.
EU officials have repeatedly warned that excluding any economic sector could hand the United States an early bargaining chip in what promise to be tough negotiations.
Washington says no areas should be excluded from the talks although there have been reports that it may seek an exception for some financial services.
European leaders agreed that time was of the essence as both Europe and America face the challenge of a rising Asia.
German Chancellor Angela Merkel agreed that the talks should start as soon as possible.
"We need to start the negotiations quickly and show ambition so that in the foreseeable future -- and I'm talking a few years' time -- we can reach agreement," Merkel told reporters.
"We've tried a couple of times before and now we have an obligation to reach a successful conclusion. And we must really work quickly because there are various free-trade agreements being negotiated in different parts of the world, for example between the USA and the Pacific region."
European Council president Herman Van Rompuy said there was "too much at stake" to be bogged down in disputes.