Angola has awarded concessions to major oil firms including BP, Total and Eni to explore its ultra-deepwater blocks, known as pre-salt blocks.

Other firms awarded concessions include ConocoPhillips, Statoil, Repsol and Cobalt International Energy, according to Reuters.

The concessions were awarded across 11 blocks, with each firm holding different stakes and some acting as operators.

Angola, which has similar underwater rock formations to Brazil, competes with Nigeria as Africa’s top oil producer.