Authorities in Brazil say that water from the Paraopeba River around the mining dam that collapsed on Friday presents a risk to humans and animals.

Three state and federal agencies asked on Wednesday that residents refrain from using water directly from the river or 100-metres around it.

The request was based on initial results from tests on the water.

The agencies also said that firefighters who have been in contact with the wet mine tailing should take safety precautions.

Dam owner and operator Vale SA is obligated to supply drinking water to affected communities.

The torrent of muddy mining waste unleashed by the dam breach killed at least 99 people, with 259 still missing.