Officials warn few survivors are expected after mining workers in canteen and on a bus are caught in a wave of iron ore waste

Hundreds of people are feared dead after a dam operated by the mining company Vale collapsed in the Brazilian state of Minas Gerais, releasing a wave of red iron ore waste and causing the worst environmental catastrophe in the country’s recent history.

Authorities say that 40 people have died, and more than 300 people remain missing according to the company. The disaster comes only three years after a similar failure of the Fundão tailings dam near Mariana – co-owned by Vale – which killed 19 people.

Speaking after the latest disaster, the local fire chief Col Edgar Estevão said 100 people had been rescued from the sea of mud released by the dam. However, Vale later released a list of 412 employees and contractors whom it had still been unable to contact, and the state governor, Romeu Zema, said he did not expect many more survivors.

“We know now that the chances of having survivors are minimal and that we will probably rescue bodies,” he said.

Brazilian television showed images of survivors being winched to safety by a helicopter after the disaster at the Feijão mine near Brumadinho, less than two hours from the state capital, Belo Horizonte.

“I saw a gigantic cloud of dust and a wave of mud. It was one wave on top of another,” one contractor, Mayke Ferreira, told the Folha de S.Paulo newspaper. Ferreira said he had been sleeping in a nearby dormitory when he was woken by an enormous crash.

It is not yet clear what caused the tailings dam to burst. However, the Brazilian environmental agency Ibama has already slapped a 250m reais (£50m) fine on Vale for violations related to the tragedy. The company has caused pollution, made the area unfit for habitation and committed other regulatory violations, Ibama said. State prosecutors have also filed a request to freeze 5bn reais in Vale’s accounts to help fund recovery works.

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Brazil’s new president, Jair Bolsonaro, visited Minas Gerais and flew over the disaster area. “We will do what is within our reach to attend the victims, minimise damages, investigate the facts, demand justice and prevent new tragedies like Mariana and Brumadinho,” he tweeted.

But locals and environmentalist had argued that the tailings dam at the Corrego de Feijão iron ore mining complex near Brumadinho presented risks as Vale sought licensing to continue and expand operations at this and another nearby mine. Bolsonaro has attacked the “fines industry” of environmental agencies such as Ibama for holding up development.

“This tragedy was only a matter of time,” said Carlos Eduardo Pinto, a prosecutor who worked on the Mariana case. “Since the Fundão tailings dam, nothing has been done to increase control of this activity.”

Facebook Twitter Pinterest Darcy Brum walks past mud that entered in the kitchen of the house of his father-in-law near Brumadinho, Brazil on Saturday. Photograph: Léo Corrêa/AP

Most of the victims of the disaster were Vale employees or subcontractors, around 100 of whom were having lunch in a canteen on the mine complex when the torrent of mud swept over them. A busload of workers was also killed, it was reported.

Maicon Vitor, 22, an electro-mechanic technician, told O Globo newspaper that he had just left the canteen when he heard the roar of the tailings dam breaking. “It came down dragging workshops, offices; the whole canteen which was in front of me went,” he said.

Fabio Schvartsman, the chief executive of Vale, said he was devastated by the tragedy. “Most of those affected were Vale employees,” he said. “I’m completely torn apart by what happened.”

Vale said the 86-metre-high tailings dam at the Corrego de Feijão open-cast, iron ore mining complex was built in 1976 and held 11.7m litres of mining waste. It was being decommissioned and had been pronounced safe in inspections.

Facebook Twitter Pinterest Mud and waste from the mining disaster in Minas Gerais. Photograph: António Lacerda/EPA

But the National Civil Society Forum for Hydrographic Basins, a network of civil society groups, said that it had urged the authorities not to grant Vale a licence to continue operations there.

“The population of Casa Branca is very worried, with good reason,” Julio Grillo from Ibama, told a meeting on 11 December, according to minutes obtained by the Observer.

Speaking on condition of anonymity, an official at the state environment agency asked why the company had built a canteen at the foot of the dam. “How can you approve a dam like this with the guy building an administrative centre with canteen at the foot of the tailings dam?”

It cost billions to clean up after the Mariana disaster in 2015, which polluted the drinking water of hundreds of thousands. Yet no individual was ever held responsible. “Cases like these are not accidents but environmental crimes,” Greenpeace Brazil said in a statement.

“I hope now they will create a new way to mine that doesn’t mount up waste, a safe way of working that does not leave widows,” said Sandra Quintao, a survivor of the Mariana disaster.

The Mariana dam was operated by Samarco, a joint venture between Vale and BHP Billiton, an Anglo-Australian mining giant.