Roberto Azevedo of Brazil on Tuesday vowed to revive the deadlocked World Trade Organization, as he was confirmed formally as the incoming leader of the 159-nation body which sets the rules for global commerce.

"I will continue to work with you in a new -- and very challenging -- capacity," Azevedo, who is still officially Brazil's ambassador to the WTO, told a session of its ruling General Council which approved him as its next leader.

"I have been working in and with this organisation continuously for the last 15 years. I have seen it in much better days. I pledge to all members that I will work with them, with unwavering and steadfast determination, to restore the WTO to the role and pre-eminence it deserves and must have," he said.

A key role of the WTO's director general is to work to advance talks on liberalising international trade -- and Azevedo will have his work cut out, given the current state of play.

The WTO's "Doha Round" talks, launched at a summit in Qatar in 2001, aim to produce a wide-ranging accord on opening markets and removing trade barriers such as subsidies, excessive taxes and regulations, in order to harness international commerce to develop poorer economies.

But differences over the give and take needed to strike a deal have sparked clashes notably between China, the European Union, India and the United States, meaning Azevedo will need to build bridges fast.

The 55-year-old will take the helm on September 1, when the WTO's current director general Pascal Lamy wraps up his second four-year term in charge.

Frenchman Lamy, 66, is a former trade chief of the European Union and became head of the Geneva-based WTO in 2005.

The WTO was spun in 1995 out of the General Agreement on Tariffs and Trade, created after World War II to lower barriers to global commerce.

Career diplomat Azevedo has been Brazil's ambassador since 2008, after past stints including as its chief litigator at the WTO.

The WTO's director general is not elected, but chosen via diplomatic efforts to identify which candidate is most likely to enjoy the broadest support.

After seven other candidates fell earlier in the race, Azevedo pipped Mexican trade heavyweight Herminio Blanco in last week's third round, with his victory underlining emerging powerhouse Brazil's new diplomatic clout.