Rio de Janeiro, Apr 5 (IANS/EFE): A total of 71 oil companies are expected to take part in an auction of Brazilian exploration blocks next month, the National Petroleum Agency, or ANP, said.

The list includes Spanish companies CEPSA and Repsol, as well as Colombia's Ecopetrol, Hupecol and Trayectoria and Panama's Pacific and Petrosynergy.

Also among the prospective bidders are Exxon and Chevron, France's Total, Italy's Enel, Britain's BP and Shell and Brazilian state-controlled oil company Petrobras.

A total of 289 exploration blocks in 11 sedimentary basins, encompassing an area of 155,800 sq. km, will be up for auction in the 11th licensing round, scheduled for May 14-15.

The majority of the blocks - 166 - are located offshore in the Atlantic, 94 of them deepwater, while the remaining 123 are onshore blocks.

Brazilian authorities excluded from this licensing round the highly promising pre-salt region, which comprises a series of recently discovered, ultra-deep fields off the coasts of the southeastern states of Espirito Santo, Rio de Janeiro, Sao Paulo and Santa Catarina.

That highly promising oil frontier, one of the world's biggest discoveries in recent decades, is so-named named because its fields are located under water, rocks and a shifting layer of salt at depths of up to 7,000 meters below the surface of the Atlantic Ocean.

An initial auction of pre-salt blocks is scheduled for November, but development of those reserves will be governed by a new oil law that will reduce companies' profits.