NEW DELHI: WTO ministers agreed Friday to resume high-level negotiations to clinch a new global free-trade pact, but despite talk of a "breakthrough" there were words of caution about the hard work ahead.

Indian Trade Minister Anand Sharma said ministers from over 35 countries meeting here for two days of talks had committed to resuming top-level negotiations in mid-September after they collapsed in July 2008.

"There has been a breakthrough," he told reporters. "The impasse in resuming negotiations has been broken."

Chief negotiators for World Trade Organisation (WTO) members would meet in Geneva on September 14 to restart negotiations, Sharma said, adding there was "a unanimous affirmation" of the need to clinch a deal after years of delay.

But US Trade Representative Ron Kirk took a step back from the 2010 deadline for a pact set in July by a meeting of top industrial and emerging nations, including the United States, for the repeatedly stalled Doha Round to conclude.

"We have missed so many deadlines," Kirk told a separate news conference at which he reaffirmed Washington's commitment to completing the round.

"Substance will drive this process, not setting deadlines and timelines," he said. "Our leaders have set as a stretch goal 2010" but that will require a "lot of hard work."

Since a failed attempt to organise a small ministerial meeting last December, the Doha Round has been restricted to low-level contacts in Geneva.

Elections in the key countries of the United States, India and most recently Japan made negotiations difficult to resume earlier, WTO observers say.

Sharma said it was too early to talk about an "end-game" for a pact, given differences on key issues of farm subsidies in rich countries and industrial product tariffs in developing nations.

"We have a long way to travel before we can safely say we are in the end-game," he said.

The Doha Round began in 2001 with the aim of creating a free-trade deal that would boost global commerce to help developing countries. Deadlock between the major trading blocs has dashed repeated attempts to forge a pact.

"Is conclusion in 2010 doable? Yes. Will it be done? I don't know," said WTO director general Pascal Lamy. "There remain tough nuts to crack in these negotiations."

India's disagreement with the United States over subsidy protection for poor farmers was widely blamed for the collapse of talks in 2008 in Geneva.

But the installation of new governments in Washington and India has fuelled hope of success sometime next year. India took the initiative in setting up the New Delhi meeting, seeking to kickstart the negotiations by getting ministers to plan a roadmap for a deal.

The world economic slump has given new impetus for an agreement that would fuel trade and could bolster global gross domestic product by up to 700 billion dollars a year, according to a think-tank report.

"This crisis actually gives all members a stronger sense of urgency" to conclude the Doha Round, China's Commerce Minister Chen Deming said Thursday, calling a deal the best bulwark against protectionism.

The Indian talks were seen as also laying ground for further progress at a meeting of leaders of the Group of 20 rich and emerging nations in Pittsburgh later this month.

Developing countries such as India, which has 235 million farmers, have been hesitant to open their markets to what they fear will be cheap crops from abroad.

Developed nations such as the United States are reluctant to abandon huge, popular agricultural subsidies and want developing countries to open their markets more to industrial products.

As ministers opened talks Thursday, thousands of farmers and social activists blocked a main New Delhi thoroughfare to demand India ditch Doha.

"The rich countries with their subsidies will destroy Indian farmers," Ajmer Singh Gill, a senior leader of Indian farm group Bharat Kisan Union, said.