Vale SA , the world's largest iron ore miner, on Tuesday vowed to take as much as 10 percent of its ore output offline in order to decommission 10 more dams like the one that burst last week, killing scores of workers and nearby residents in Brazil.

Chief Executive Fabio Schvartsman said it would temporarily paralyse operations using those dams and spend 5 billion reais ($1.3 billion) to decommission them over the next three years.

The move came as prosecutors began arresting Vale executives over the Friday collapse of a tailings dam in the Brazilian town of Brumadinho, which was hit by a torrent of mining waste that killed at least 84 people and left hundreds more missing.

The disaster raised fresh questions about the company's commitment to safety after a similar deadly dam burst just over three years ago at a nearby mine it jointly owned.

"We decided the company should, once and for all, do what it takes to remove any doubt about the safety of Vale's dams," Schvartsman told journalists in Brasilia.

The burst Brumadinho dam was one of 19 "upstream" tailings dams owned by Vale, all in the state of Minas Gerais, built with a method banned in Peru and Chile for safety reasons.