Venezuela's chief prosecutor says the government is investigating a corruption scheme involving his predecessor, Luisa Ortega.
Tarek Saab alleges that Ms Ortega, who fled abroad after being sacked, knew about a scam in the oil fields around the Orinoco river and did nothing.
Oil contractors cost the country billions in lost revenue, he said.
There was no immediate response from Ms Ortega, who has previously accused Mr Saab of corruption himself.
She has been a vocal critic of the left-wing President, Nicolás Maduro, saying he and senior members of the government are involved in multi-million dollar corruption schemes.
The allegation has been dismissed by the government, which accuses her of working with the US against Venezuela's interests.
In June, Ms Ortega was labelled a "traitor" by officials after she challenged President Maduro's plan to create a constituent assembly.
Her protest was ignored and the new assembly, which is dominated by government supporters, decided to remove Ms Ortega from office in a unanimous vote.
She was replaced by Mr Saab who is a supporter of President Maduro.
Ms Ortega accused the authorities of trying to hide evidence of corruption and human rights abuses. She added that she would work to "recover liberty for Venezuela, because we've lost it".
After she was removed from office she fled the country with her husband.
She went to the Caribbean island of Aruba off the coast of Venezuela and from there flew to Colombia in a private jet. She then travelled to Brazil.