The United States and the European Union aim to begin talks by the end of June on creating a free-trade pact between the world's top two economies.

The two sides hope negotiations to eliminate or minimise barriers for all industrial and agricultural goods could be concluded by next year.

A free-trade deal between the US and the EU would be the most ambitious since the World Trade Organisation was established in 1995, encompassing half the world's economic output and a third of global trade flows.

The proposed trade pact reflects impatience with the lack of a new global agreement to cut tariffs and ease commerce.

But after a year of preparatory discussions between Brussels and Washington, major differences remain, such as EU resistance to importing US foodstuffs that are genetically modified.

"This is potentially a very big deal," said Michael Froman, White House deputy national security adviser for international economic affairs, a day after President Barack Obama endorsed talks in his State of the Union address.

In Brussels, EU Commission President Jose Manuel Barroso said: "These negotiations will set a standard, not only for our future bilateral trade and investment, including regulatory issues, but also for the development of global trade rules."

Once the US Congress is notified and all 27 EU states assent to the talks going ahead, the sides hope for a deal by the end of 2014 - a tight deadline in international trade talks.