(Adds nature of charges, TUV SUD statement, background, PIX available)
By Marta Nogueira
SAO PAULO, Jan 21 (Reuters) - Brazil state prosecutors have charged employees at miner Vale and auditor TUV SUD with homicide in relation to a deadly dam disaster last year, a source told Reuters on Tuesday.
In addition to the charge against employees, the source, with access to the charges, said Vale SA and TUV SUD have been charged with environmental crimes.
State prosecutors have convened a media conference to unveil the charges at 3pm (1800 GMT). They said on Twitter they will charge Vale, TUV SUD and 16 people, but did not offer further details.
Reuters reported earlier this month that prosecutors were set to file criminal charges in coming days.
The Wall Street Journal was first to report the nature of the charges.
Vale shares were down almost 2% after the Twitter announcement.
State prosecutors are filing charges almost a year after the catastrophic dam collapse, which took place in the town of Brumadinho in the state of Minas Gerais and killed more than 250 people. The collapse of the Vale tailings dam was one of the world's deadliest mining accidents and knocked $19 billion off Vale's market value in a single day.
In a statement, TUV Sud said it was cooperating with authorities and could not comment further on the case as investigations were continuing.
Vale did not immediately respond to a request for comment. (Reporting by Luciano Costa, Marcelo Rochabrun and Marta Nogueira Editing by Chizu Nomiyama and Bill Berkrot)
Our Standards: The Thomson Reuters Trust Principles.