RIO DE JANEIRO, Sept. 28 (Xinhua) -- The Brazilian government collected 6.820 billion reales (about 1.705 billion U.S. dollars) by auctioning four areas of the pre-salt oil zone, in the deep water of the Atlantic, the Brazilian National Petroleum Agency (ANP) said Friday.

The two top bidders were Exxon of the United States and the Anglo-Dutch company Shell, which were awarded the two largest bidding areas. A total of 12 companies from around the world took part in the auction.

This was the last bidding process during the administration of President Michel Temer.

ANP president Decio Oddone called the bidding outcome extraordinary.

In addition to the 6.8 billion reales, the four bidding areas required investments totaling nearly 1 billion reales (about 250 million U.S. dollars).

Two of the auctioned areas are close to the maritime basin of Campos, off the coast of Rio de Janeiro. Two others are off the coast of the state of Sao Paulo, both in southeast Brazil.

The pre-salt zone has large volumes of crude that, once tapped, will convert Brazil into one of the leading producers of petroleum in the world.

The wells are in extremely deep waters below a extensive salt cap, which can reach 2,000 meters of thickness in some cases.?