BELO HORIZONTE, Brazil (Reuters) - Federal prosecutors investigating the deadly dam spill in November at the Samarco iron ore mine, owned by Vale SA (>> Vale SA) and BHP Billiton (>> BHP Billiton Limited), will decide in coming weeks whether to charge the company and executives, a prosecutor in the case said on Tuesday.

A police investigation accused Samarco in June of willful misconduct, saying the company ignored clear signs the dam was at risk of collapsing. The investigation is now with prosecutors, who are deciding whether to file charges.

Samarco denies any wrongdoing.

"The task force is at this moment concluding the analysis of the documents from the investigation," prosecutor Eduardo Santos de Oliveira said in an interview, declining to comment further on what charges might be brought or whether the case might be dismissed.

He said a decision was expected in September.

De Oliveira's comments come the day after Samarco, Vale and BHP published a report into the cause of the dam collapse, which killed 19 people and resulted in Brazil's worst environmental disaster.

The report found the spill was caused by drainage and design flaws but stopped short of assigning blame, saying such a verdict was outside its scope.

De Oliveira said the report, which was commissioned by the mining companies and carried out by law firm Cleary Gottlieb Steen & Hamilton, would be considered in any decision to bring charges but that at first glance the report appeared to have little new information.

(writing by Stephen Eisenhammer; Editing by Cynthia Osterman)

By Marta Nogueira

Stocks treated in this article : BHP Billiton plc, BHP Billiton Limited, Vale SA