Brazilian authorities have ordered the mining company Vale to evacuate hundreds of people from the vicinity of a dam in Minas Gerais, two weeks after a dam breach at another Vale mine in the state killed an estimated 300 people.

Vale said it was evacuating 500 people from three communities around the Sul Superior tailings dam at the Gongo Soco mine, near Belo Horizonte, on the orders of the national mining agency. It said it was a preventive measure after an engineering consulting firm, Walm, refused to give the dam a declaration of stability.

Warning sirens sounded and evacuations began at about 1am local time, TV Globo reported. “Attention, attention. This is an emergency … Abandon your homes immediately and follow the escape route,” the announcements said.

In a separate development, 200 people were evacuated from Itatiaiuçu, in the same state, after an alert was issued over a dam operated by ArcelorMittal. The world’s largest steel firm said that “after very careful consideration” it had taken the decision to put in practice an evacuation plan related to its dormant Serra Azul tailing dam.

There has been growing unease among people living near tailings dams in Brazil since the Brumadinho disaster last month. Police arrested three Vale employees and two engineers from the São Paulo offices of the German company TÜV SÜD, which provided stability declarations for the Brumadinho dam. Employees have told the Guardian that the dam had a leak last year.

On Friday authorities also closed a port terminal operated by Vale in Vitoria, in the south-eastern state of Espírito Santo because of pollution issues. The municipality of Vitoria said on Thursday it had fined Vale 35m reais (£7.2m) for throwing mining residues into the sea.