(Bloomberg) -- The stability of Vale SA’s Sul Superior dam slid into a critical condition, prompting a warning siren to be activated Friday, the company said, citing an independent auditor.

About 500 people have already been evacuated Feb. 8 from the area near the dam located at the Gongo Soco mine in the city of Barao de Cocais in Minas Gerais state. The miner launched a protocol to initiate level 3 of the Mining Dams Emergency Action Plan, it said.

The world’s biggest iron ore producer, which is expected to release its fourth-quarter figures next Wednesday, is preparing to restart the Brucutu iron ore mine, after the project was shut in the aftermath of the deadly dam disaster in Brumadinho in January. Investors have been weighing Vale’s production woes and increased iron ore prices, as the stock extended its year-to-date loss.

Under intense scrutiny, the Brazilian company has removed executives following the departure of its chief executive officer, Fabio Schvartsman. Vale has shut in more than 90 million tons of output in the aftermath of the dam spill, roiling the global iron-ore market.

To contact the reporter on this story: Vinícius Andrade in São Paulo at vandrade3@bloomberg.net

To contact the editors responsible for this story: Courtney Dentch at cdentch1@bloomberg.net, Linus Chua, James Ludden

©2019 Bloomberg L.P.