Top officials from Brazil, the European Union and the United States meet in Rio de Janeiro Friday and Saturday to try to narrow differences, which are holding up a wider deal on cutting barriers to commerce.

"I don't think it would be a decision" forthcoming from the talks, Mandelson said at a news conference in Buenos Aires.

Rather, he said, the meeting "will be an opportunity to understand the differences that exist among the key players to see how we could narrow the gap between us."

Mandelson will join EU chief Pascal Lamy and US Trade Representative Rob Portman for the talks hosted by Brazil's Foreign Minister Celso Amorim.

The meeting comes a month before an April 30 deadline to agree on data aimed to conclude their Doha Round trade agreement by year-end.

"We are now in an important period. I believe the moment of truth is approaching," said Mandelson, who earlier met with several Argentine officials, including Economy Minister Felisa Miceli.