RIO DE JANEIRO - The death toll from Brazil's tragic dam disaster in southeast Minas Gerais state has climbed to 166, the state civil defense agency said on Wednesday.

The agency's Lt. Col. Flavio Godinho told the press that another 155 people are still missing since the tailings dam that contained tons of toxic waste from an iron-ore mine collapsed on Jan 25, burying parts of the town of Brumadinho under mountains of mud.

Efforts to locate the bodies of the missing continue though rescuers are finding increasingly fewer bodies as the remaining victims lie buried under as much as 15 meters of mud, he said.

Authorities have identified 160 of those killed, most of whom are employees of mining giant and dam owner Vale and residents of surrounding communities.

The rescue operation continues with 327 firefighters and 43 pieces of heavy machinery, including trucks and excavators, eight aircraft and 12 search and rescue dogs.

The sea of mud is believed to have washed away Vale administrative offices and a cafeteria where hundreds of employees were having lunch when the dam broke.

Five people who had been arrested for their role in validating the safety of the dam just months before it collapsed were released last week pending further investigation.

The Vale company began to build a bridge leading to the collapsed dam, to replace an old one which, along with other buildings in the small rural town of Brumadinho, was destroyed by a rush of toxic mud unleashed after the dam collapsed, said Flavio Godinho, spokesman for the state civil defense department.

The incident marks the second tailings dam collapse in three years at a Vale-owned mining operation in Brazil, flooding communities and fields with toxic sludge.

In November 2015, a tailings dam partly-owned by Vale ruptured in Mariana, also in Minas Gerais, destroying an entire community and killing 19 people. It was considered Brazil's worst environmental disaster.