“We know that the amount of damages could be much greater, but the agreement establishes a firm legal guarantee,” said Brazilian prosecutor Carlos Eduardo Ferreira Pinto.
Samarco is a joint venture between BHP and Brazilian mining group Vale.
A dam controlled by the group burst — flooding villages and rivers with thick, toxic mud.
The company was originally fined 250 million reals on Friday. BHP has put all its joint-venture projects under review.