Brazilian state-run energy giant Petrobras (PBR) will offer tenders for 28 deepwater drill rigs this month, the company said in a statement Friday.

The rigs, which will include drill ships and semi-submersibles, are expected to be delivered between 2013 and 2018, Petrobras said.

"The board of directors approved the strategy for construction of 28 new drilling rigs to be built in Brazil, with increased national content, to explore ultra-deepwaters including fields located in the subsalt," Petrobras said.

A value for the tenders was not divulged. Brazil's government, however, has pledged 4 billion Brazilian reals ($2.2 billion) in financing to guarantee construction of the rigs, Petrobras said.

The first phase of the tender will be for a minimum lot of nine rigs, including at least seven drill ships. A single shipyard will win the tender, Petrobras said, in order to make the necessary investments to fulfill the order and make it economically feasible.

The subsalt finds were made under a thick layer of salt in the Santos Basin off the coast of Sao Paulo and Rio de Janeiro states. The oil lies under more than 2,000 meters of water and a further 5,000 meters under sand, rock and a shifting layer of salt.

-By Jeff Fick, Dow Jones Newswires; 55-21-2586-6085; jeff.fick@dowjones.com