RIO DE JANEIRO, Jan. 30 (Xinhua) -- The death toll from Brazil's mining dam collapse in southeastern Minas Gerais state has reached 99, local authorities said on Wednesday.

A total of 259 people are still missing, according to the state civil defense department.

Of the 99 dead, 57 have been identified.

The number of people left homeless increased from 135 to 175, according to the state government.

Most of the victims are employees of mining giant Vale, which owned the dam. About 100 workers were having lunch at the company's cafeteria located just below the dam when it burst. Rescue efforts have yet to locate the building, which may have been swept away by the mudslide, according to experts.

The dam held at least 13 million cubic meters of industrial waste that is estimated to have spread over an area of 125 hectares.