Developed nations and developing countries on Sunday agreed to resume the Doha round of talks after it stalled in July, but they failed to reach a consensus on a definite date for the negotiations.

The accord came after a dialogue was held here between trade ministers from the G-20 group of developing nations and developed countries, represented by the United States, the European Union (EU) and Japan.

What happened in July was "a serious accident," said the WTO director general Pascal Lamy at a press conference at the close of the G-20 meeting.

But "We have been able to move ahead in Rio de Janeiro," and all the parties at the Rio meeting agreed that negotiations should resume, he added.

"By mid-March of next year we have to know if there is a deal in the making or not," Lamy said, though a definite date for formal negotiations had not been decided at the meeting.

The WTO chief said that the talks would be focusing on the issue of cutting farm subsidies that favor rich nations, and on the other hand, enable the rich nations to gain increased market access in developing countries.

EU trade commissioner Peter Mandelson said that the EU nations could offer improved customs rates to help resume the Doha Round of talks.

However, the EU will only do so if the United States takes the same stance, and if developing countries make greater concessions on their industrial goods and services markets, said Mandelson, who is on an official visit to Brazil.

"This is a very difficult moment for the negotiations," Mandelson said. "But the commitments we have made are predicated on the idea that others will also make an effort in order to reach the end of negotiations."

Mandelson said that the Rio meeting had given "a very clear yes" to resuming trade talks.

He also called for technical studies on the question of farm subsidies and market access.

The top U.S. trade negotiator Susan Schwab said that the United States "is committed to finding a successful outcome for this round if there is one to be found."

But it needed extra efforts on the part of developed and developing countries alike, added Schwab, cautioning that immediate results were not realistic.

At the Rio meeting, the United States was blamed for the collapse of talks in July by a number of representatives, who believed that little progress is possible before the U.S. congressional elections in November.

Mandelson underlined the need to restart negotiations before the end of this year after the U.S. legislative elections, which could change the political landscape there.

"We do not know if it will be renewed," he said. "And in 2007, that country will begin to discuss a (planned new) agriculture law. Agreements must be reached before then."

For a deal to be reached, the period between November 2006 and March 2007 is crucial, Mandelson said.

The September 9-10 meeting of the G-20 developing nations in Rio marks the first time international trade officials have met since the Doha Round of World Trade Organization talks suspended in July, largely because of  developing countries' demands for more shares in the agricultural markets of developed countries and also regarding the latter's subsidies in domestic agriculture.

The G-20 was formed in 2003. With Brazil as one of its leading member nations, the group also consists of Argentina, Bolivia, Chile, China, Cuba, Egypt, the Philippines, Guatemala, India, Indonesia, Mexico, Nigeria, Pakistan, Paraguay, South Africa, Thailand, Tanzania, Uruguay, Venezuela and Zimbabwe.