(Recasts throughout, adds Petrobras comment on sale at hearing)
BRASILIA, Aug 16 (Reuters) - Brazilian prosecutors intend to open a formal investigation into last year's controversial sale of the Argentine subsidiary of Petrobras, Brazil's state-controlled oil company, a lawyer representing some Petrobras shareholders said on Wednesday.
Petrobras, formally known as Petroleo Brasileiro SA , sold its 67.2 percent stake in Petrobras Argentina SA for $892 million to Pampa Energia SA, Argentina's largest power company.
The sale has already drawn scrutiny from Brazil's Congress and a federal audit court and lawyer Felipe Caldira 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, told Reuters he spoke on Tuesday to prosecutors on a task force in Curitiba leading the Car Wash probe 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 did not respond to requests for comment.
Lawyers for Pampa and Petrobras said the sale was conducted in a transparent and competitive manner and that Pampa made the best offer.
Petrobras bought the Argentine unit from energy conglomerate Perez Companc in 2002 for $1 billion, plus $2 billion in debt.
The sale 14 years later for much less has sparked controversy in Brazil and executives from Petrobras and Pampa Energia, as well as lawyer Caldeira, testified at a congressional committee hearing in Brasilia on Wednesday.
Petrobras' legal manager for acquisitions and divestment, Claudia Zacour, 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
Aldemir Bendine, chief executive officer of Petrobras at the time of the sale, was jailed last month 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.
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 percent 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 Wednesday's hearing. (Editing by Jeffrey Benkoe and Tom Brown)