Leaders fire starting gun for EU-US trade talks

He added that the agreement, between the two largest world economic blocs, would have a "greater impact than all the other trade deals on the table put together."

US President Barack Obama revealed the first round of negotiations would take place in Washington in July.

"I believe we can form a economic alliance as strong as our diplomatic and security alliances," he noted.

He said "TTIP is going to be an important priority of mine and my administration."

The treaty aims to eliminate "behind border barriers" by harmonising technical and regulatory standards.

EU trade ministers signed off on the bloc's negotiating mandate late on Friday (14 June) after the French government secured an exemption for its cultural sector.

Most EU countries want everything to be on the table.

But for its part, the US is still expected to try to rule out financial services from the scope of the deal.

Public procurement rules and standards relating to the pharmaceutical industry are also expected to cause problems.

The commission estimates that a full-blown EU-US trade deal going beyond conventional tariff barriers and harmonising all standards could be worth €100 billion per year.

It would amount to the EU equivalent of an additional 0.5 percent of EU GDP and would create 2 million new jobs.

A more limited deal failing to go beyond tariffs would limit the economic benefits to under €25 billion.

EU trade officials have been trying to lay the groundwork for a trans-atlantic trade deal for nearly 20 years.

The launch represents something of a coup for Cameron, who is keen to emphasise the EU's leverage in international trade as he bids to take the wind out of the sails of his Conservative party's eurosceptics.

Although most of the EU's bilateral trade deals have taken an average of three years to conclude, both the European Commission and the Obama administration are keen to make the negotiations as speedy as possible.

Trade commissioner Karel de Gucht wants to conclude talks before the commission changeover in September 2014.

The Americans would like to strike a deal before the next round of Congressional elections in November 2014.

"We intend to move fast," said commission President Jose Manuel Barroso.

"Two years ago very few would have bet that we would be able to do this," he added.