Mineral residue from the rupture of two tailings dams in the Brazilian state of Minas Gerais in November has contaminated an area of 168 square kilometers of the Atlantic Ocean, a government agency said on Thursday.

According to data from the Espirito Santo State Environmental Institute (IEMA), mud and sludge spread from Minas Gerais to the coast of Espirito Santo quickly and have since covered 168 square kilometers of ocean along the coast.

Since the dams burst on Nov. 5 at the Samarco mine near the town of Mariana, unleashing a torrent of 63 million cubic meters of mud, this disaster has become the worst environmental tragedy in the history of Brazil.

The sludge has left 17 dead and two missing as well as contaminated the Doce river, several tributaries and parts of the ocean. Thousands of animals living in and near these waterways have died as a consequence.

Brazilian authorities have issued tough economic sanctions on Samarco and have frozen the Brazilian assets of Samarco's joint owners, Vale and BHP Billiton.