A Brazilian court on Friday froze 300 million reais ($78 million) from the accounts of Samarco, operator of an iron ore mine where a dam burst killed at least 10 people last week.
The court in Mariana, a city close to the disaster in southeastern Brazil, said in a statement that the blocked funds could only be used for paying damages to victims.
Samarco is owned by Australia-based BHP Billiton, the world's largest mining company, and Brazil's Vale, the largest iron ore miner.
On Thursday, Brazilian President Dilma Rousseff announced "preliminary" fines amounting to $67 million and indicated there would be others.
The breaking of two dams at a waste pond at the mine on November 5 unleashed a torrent of muddy water that buried the village of Bento Rodrigues and caused widespread interruption of drinking water supplies in the area.
A further 18 people are still missing and more than 630 have been forced from their homes.
The clean-up cost could top $1 billion, according to Deutsche Bank.
Judge Frederico Goncalves said he ordered the funds frozen Friday because "the future financial health of Samarco, in my understanding, is highly uncertain."
However, he also called for Samarco, a major employer in the region, not to be "demonized."
Vale announced separately that it was buying 14.5 million liters of drinking water for local people, saying this should be enough to provide all inhabitants with up to three liters each day for 12 days.
"We are doing everything, absolutely everything that we can in relation to human rights so that people affected can be helped," said a spokesman for Vale.