"We were so close to getting this done," U.S. Trade Representative Susan Schwab told reporters at World Trade Organisation headquarters after countries failed to compromise over measure to protect farmers in poor countries.

"The U.S. remains committed to the Doha round. This is not a time to talk about a round collapsing," said Schwab, who looked frustrated and distressed. "The U.S. commitments remain on the table, awaiting reciprocal responses."

As failure looked likely, New Zealand's trade minister, Phil Goff, held out hope for Doha talks continuing at a later date. "I hope ... that what we've achieved this week can be used at least to build on as a foundation for the future," he said.

However failure of the talks to find a broad agreement on the Doha trade round, could delay any global agreement on trade liberalisation for several more years, experts say.

The negotiations for a global deal trade began in 2001, shortly after the September 11 attacks on the United States, in the hope of boosting the world economy and helping poor countries.

They have lurched from crisis to crisis and risk further years of delay without a breakthrough now because of the U.S. presidential election in November and other factors.

Washington had opposed a push from India, China and Indonesia to secure measures to protect their farmers if faced with sudden surges of cheap farm imports.

Earlier, European Union Trade Commissioner Peter Mandelson urged parties to seek compromise. "If people don't want this deal, there's no better deal coming along and we just have to consider, if this fails, what they will lose," he said.