RIO DE JANEIRO (REUTERS) - Brazilian mining firm Vale SA activated alarms in areas below three tailings dams on Wednesday night (March 27) due to an elevated risk of rupture, amid a tense atmosphere in Minas Gerais state, where a dam burst in January killed about 300 people.

The company activated alarms in areas downstream of the B3/B4 dam and the Forquilha I and Forquilha III dams as a"preventative measure", after the structures failed to receive a safety certification from independent auditors.

There will be no new evacuations from the area, Vale said, as residents had vacated the relevant danger zones in February.

In late January, a tailings dam at Vale's Corrego do Feijao mine in Minas Gerais ruptured, unleashing a torrent of sludge that killed hundreds.

It was the second deadly rupture of a Vale-linked dam in Minas Gerais in just over three years.

Since then, the firm has pledged to decommission dams built in a similar fashion to the ones that burst, and several executives, including the chief executive, have stepped down.