Brazilian prosecutors plan to investigate the controversial sale in 2015 of the Argentine subsidiary of Petrobras (NYSE: PBR), Brazil's state-controlled oil company, lawyer Felipe Caldeira, said on Aug. 16.

Petrobras sold its 67.2% stake in Petrobras Argentina SA for $892 million to Pampa Energia SA (NYSE: PAM), Argentina's largest power company.

The sale has already drawn scrutiny from Brazil's Congress and a federal audit court.  Caldeira said prosecutors were now looking into it as part of Brazil's sweeping “Car Wash” anti-corruption investigation.

Caldeira, representing a group of minority Petrobras shareholders, said he spoke to prosecutors leading the Car Wash probe on Aug. 15 and gave them information on the sale.

“They are very interested and will investigate this,” said Caldeira, who filed a civil case in a Rio de Janeiro court in May alleging that the sale fetched a below-market price and was harmful to the interests of minority shareholders.

Federal prosecutors in Curitiba said the task force had not met with Caldeira, but said that any relevant information about the case would be studied.

Petrobras bought the Argentine unit from energy conglomerate Perez Companc in 2002 for $1 billion, plus $2 billion in debt.

The sale sparked controversy in Brazil 14 years later and led lawmakers to call on Caldeira, Petrobras and Pampa executives to testify before a committee hearing on Aug. 16.

The controversy has grown since Aldemir Bendine, CEO of Petrobras at the time of the sale, was jailed in July on suspicion he received bribes from construction conglomerate Odebrecht in a political graft scandal that has led to the arrest of dozens of executives and politicians.

Pampa's executive VP and legal director Diego Salaverri told the committee the sale was transparent, it was competitive and his company made the best offer that was a “fair” price in a depressed market.

Oil prices had dropped drastically from $100 to $30 and a climate of uncertainty prevailed in Argentina, which had currency controls and a ban on remittances, Salaverri said.

Claudia Zacour, Petrobras' legal manager for acquisitions and divestment, told the committee the sale of Petrobras Argentina was part of the Brazilian oil company's divestment plan to reduce debt and focus on core activities.

The net positive result for Petrobras of owning and selling the Argentine unit was $1.6 billion when taking into account intercompany loans, the sale of some of its assets and the distribution of dividends, Zacour said.

Brazil's federal audit court has said it was investigating the sale of Petrobras Argentina at the request of a senator, but has not concluded its findings.

In response to Caldeira's lawsuit, a federal judge in Rio de Janeiro sent Argentine authorities a request that the chairman of Pampa Energia, Marcos Marcelo Mindlin, testify in the case.

With a majority stake, Pampa SA, Mindlin's holding company, continued its takeover of Petrobras Argentina in November by acquiring 11.85% held by the Argentine state pension system ANSES.

The transaction is being investigated by Argentine judge Claudio Bonadio, who ordered the search and seizure of documents from government offices in May, in a case brought by center-left lawmaker Victoria Donda.

“The fund's shares were sold very cheap, and we want to know why because thousands of pensioners lost money,” Donda told Reuters in Brasilia, where she traveled to attend the Aug. 16 hearing.