GENEVA (Reuters) - Roberto Azevedo, a Brazilian trade diplomat, will be the next head of the World Trade Organization, a diplomatic source said on Tuesday after the results of the contest to succeed France's Pascal Lamy were given in a confidential meeting.

Azevedo beat Mexico's former trade minister Herminio Blanco in the three-round competition, becoming the first Latin American to head the trade group since its creation in 1995.

Sources involved in the process said Blanco had got a boost from narrowly winning the European Union's support, although the EU made clear that it could accept either man, giving Azevedo wider support among the WTO's 159 members.

The result of the six-month competition, which attracted a field of nine candidates, easily the largest in the WTO's history, will be formally announced on Wednesday. Azevedo is expected to be confirmed as the winner at a meeting on May 14.

He will take over from Lamy on September 1 and almost immediately faces a baptism of fire - the WTO's biennial ministerial meeting, to be held in Bali in December.

The Geneva-based organization is struggling to get an agreement lined up for Bali, despite massively pruning its ambitions after failing in a 10-year attempt to conclude the "Doha" round of trade liberalization talks.

The Bali deal aims to cut bureaucracy by standardizing customs procedures, lending a potential trillion dollar boost to the world economy, while introducing new rules to promote food security and concessions for poorer countries.

(Reporting by Tom Miles; Editing by Stephanie Nebehay and Louise Ireland)