SAO PAULO, Feb 6 (Reuters) - Brazilian iron ore miner Vale SA was made aware of problems with sensors designed to monitor the structure of a dam that ended up bursting, killing an estimated 300 people, two days before the disaster, Globo TV reported on Wednesday.Namba also said he felt "pressured" by Vale employees to certify the dam that later burst in Brumadinho was stable
An exchange of emails between executives at Vale, outside auditing firm T?oeV S?oeD and a third inspection firm on Jan. 23 discussed discrepancies in data obtained from automated instruments installed in the dam, as well as five other such instruments which appeared not to be working," the report said, citing the deposition of a T?oeV S?oeD engineer, Makoto Namba.
Namba, one of two T?oeV S?oeD employees who were arrested in the days after the dam burst, said in the deposition that he was not made aware of the discrepancies until after the dam broke.
Namba also said he felt "pressured" by Vale employees to certify the dam that later burst in Brumadinho was stable. He was freed on Tuesday.
Vale declined to comment on the investigation but said it was cooperating with the probe. T?oeV S?oeD declined to comment on the report, noting that it has hired two law firms to help it probe its role in auditing the dam.
Reuters could not confirm the contents of the deposition.
The deposition was the latest in a series of reports to raise questions about whether there were missed warnings ahead of the dam burst, which unleashed an avalanche of toxic mud onto the surrounding countryside, destroying a corporate dining hall and a country inn among other buildings.
A report Vale commissioned last year from the same firm raised concerns over its drainage and monitoring systems, although it certified the dam as stable.
Reuters reported last week that one Vale executive identified concerns around its tailings dams as early as 2009, although the company did not implement several steps he pointed to that could have prevented or lessened the damage from the Jan. 25 dam collapsed.
(By Christian Plumb; Editing by Lisa Shumaker)
Click here for complete coverage of the dam burst at Vale's C??rrego do Feij??o mine.