Read More: BHP, Vale Offer Brazil $25.7 Billion to Cover Dam Disaster (1)

Silveira said the proposal is technically and economically inappropriate because it reduces the companies’ obligations, transferring them to the federal government and the states. Brazil’s general attorney’s office confirmed in a statement the proposal was officially rejected Friday.

Brazil’s mines and energy chief signaled that President Luiz Inacio Lula da Silva’s government is studying legal ways of putting pressure on Vale, BHP and Samarco to speed up a settlement, without giving details.

“Vale and BHP either make an agreement or they will face the full rigor of the law,” Silveira said.

Minas Gerais state government said in a statement that it sees room for adjustments in the companies’ proposal with a focus on speeding up the reparation, adding that there has been progress compared with the previous $8.2 billion (42 billion reais) offer. State Planning Secretary Luisa Barreto criticized what she called “a unilateral decision by the federal government” to reject it.

A final settlement in the 2015 Mariana dam collapse, which killed 19 people and contaminated waterways in two Brazilian states, would remove a major legal shadow hanging over the companies and cement a reparation schedule for victims in what is Brazil’s biggest environmental disaster.

Silveira said he is concerned that BHP could expand operations in Brazil before giving reparation to the victims of Samarco dam break, if a bid to buy rival miner Anglo American Plc is successful. Anglo holds Minas Rio iron ore mine in Minas Gerais, one of the two states directly affected by Samarco’s dam collapse.