BRASILIA, Jan. 31 (Xinhua) -- Brazil's government will ask congress to urgently review existing regulations to ensure dam safety in wake of last week's dam collapse, the president's spokesperson Otavio do Rego Barros said on Thursday.

According to official figure, some 3,000 dams in the country are considered at "high risk" of collapsing, like the tailings dam that burst on Friday in Brumadinho, Minas Gerais state, killing at least 110 people with near 240 persons still missing.

The failure of the dam used to store iron-ore waste of mining operations conducted by mining giant Vale has released vast amounts of toxic waste, repeating the tragedy in 2015 in the Minas Gerais town of Mariana.

The 2015 dam failure had sent toxic sludge eventually to the Atlantic, polluting land and rivers along the way, including water sources that local communities relied on for drinking water. It is regarded as the worst environmental disaster in Brazil's history.