The top U.S. trade negotiator said on Sunday before meeting a group of developing nations the United States was committed to a successful outcome of current world trade talks.

We will do what it takes. If there is potential for a successful round we will find it, U.S. Trade Representative Susan Schwab told journalists, in reference to the World Trade Organization's Doha round of talks, which collapsed in July.

She spoke briefly after meeting WTO Director General Pascal Lamy and Japanese Agriculture Minister Shoichi Nakagawa in Rio de Janeiro.

Schwab, who is attending a meeting of the so-called G20 group of developing nations, is also due to meet European Union Trade Commissioner Peter Mandelson later on Sunday.

But she cautioned against any major breakthrough during the weekend meeting.

I don't think any of us is expecting a turnaround in 24 hours, but we know that it's a step that we have to take and we have to take one step at a time to see if we can save the Doha round, Schwab said.

The Rio gathering marks the first time the G20 has met since talks over the Doha round collapsed.

The United States, EU and Japan were joining efforts by the G20 to revive the talks.

There is always time to resuscitate the talks if the political will is there. President Bush is committed to a successful outcome of the Doha round, Schwab said.

She was referring to the expiration in July 2007 of Bush's so-called fast track negotiating mandate by which Congress must either approve or reject any eventual trade accord, without making any amendments.

Since the WTO's Doha round of talks began in 2001, Brazil, India and other countries that rely heavily on agriculture exports have focused on trying to cut subsidies and trade barriers by the United States and the European Union.

European nations and the United States have been unwilling to reduce aid to cotton, sugar and other products unless they get more access to services and manufacturing in developing nations.