The search for potential survivors of a dam collapse in Brazil has been suspended amid fears that another nearby dam owned by the same company was also at risk of breaching.
Authorities are evacuating several neighbourhoods in the southeastern city of Brumadinho that are within range of the B6 dam, owned by the Brazilian mining company Vale.
There was no immediate word on how many people were evacuated.
People observe the mud masses after the break of a dam at the Feijo iron ore mine Source: Getty Images
Spokesman for firefighters in Minas Gerais state Pedro Ahiara said on Sunday the risk of the other dam breaking continues.
Even before the latest news, hope that loved ones had survived a tsunami of iron ore mine waste from Friday's dam collapse in the area was turning to anguish and anger over the increasing likelihood that many of the hundreds of people missing had died.
Company employees at the mining complex were eating lunch on Friday afternoon when the first dam gave way.
By Saturday night, when authorities called off rescue efforts until daybreak, the toll stood at 40 dead with up to 300 people estimated to be missing.
All day Saturday, helicopters flew low over areas encased by a river of mud and mining waste as firefighters dug frantically to get into buried structures.
Sonia Fatima da Silva, whose son had worked at Vale for 20 years, was trying to get information about him.
"I'm angry. There is no way I can stay calm," she said.
"My hope is that they be honest. I want news, even if it's bad."
Minas Gerais governor Romeu Zema said by now most recovery efforts will entail pulling out bodies.
The flow of waste reached the nearby community of Vila Ferteco and an occupied Vale administrative office.
On Saturday, rooftops poked above an extensive field of the mud, which also cut off roads.
Some residents barely escaped with their lives.
The river of sludge from the burst dam in Minas Gerais, Brazil swept away cars as well as people. (AAP) Source: AAP
In addition to the 40 bodies recovered by Saturday night, 23 people were admitted to hospital, according to the Minas Gerais fire department.
There had been some signs of hope earlier on Saturday when authorities found 43 more people alive.
The company said that while 100 workers were accounted for, more than 200 were still missing.
Vale chief executive Fabio Schvartsman said he did not know what caused the collapse.
The rivers of mining waste raised fears of widespread environmental contamination and degradation.
Over the weekend, state courts and the justice ministry in Minas Gerais froze about $US1.5 billion ($A2.1b) from Vale assets for state emergency services and told the company to report on how it would help the victims.
Brazil's attorney general Raquel Dodge promised to investigate the mining dam collapse.
A home lays in ruins after a dam collapsed near Brumadinho, Brazil on Friday. Source: AAP
"Someone is definitely at fault," she said.
Another dam administered by Vale and Australian mining company BHP Billiton collapsed in 2015 in the city of Mariana, Minas Gerais, resulting in 19 deaths and forcing hundreds from their homes.
Considered the worst environmental disaster in Brazilian history, it left 250,000 people without drinking water and killed thousands of fish.
