(Adds ruling details, sale background, comment on previous injunction)
By Jeb Blount and Marta Nogueira
RIO DE JANEIRO, Jan 26 (Reuters) - A Brazilian court blocked the 1.9-billion-real ($469 million) sale of a 40 percent stake in a natural gas unit of Petroleo Brasileiro SA to Japan's Mitsui & Co, throwing up a roadblock to the state-led oil company's efforts to cut debt by selling assets.
Judge Paulo Piropo de Abreu of the Federal Regional Tribunal in Bahia said in a ruling on Monday he issued the injunction out of concern the sale was not conducted with the transparency required by the country's public tender laws.
This could hide corrupt practices damaging to Petrobras, as the company is known, and harm public finances, he said. Piropo de Abreu said Petrobras' involvement in a corruption scandal and its move to sell $15.1 billion of assets by the end of the year required him to prevent any final sale of the Gaspetro stake until it faces a full, independent and public review.
"The time has arrived for the Judiciary to define if Petrobras is following the same practices in its sale of assets (as it has in the past)," the judge wrote. "These being: sales without public tenders, secret negotiations, suspicion of price-fixing, (and) with strong suspicion of illegality."
Petrobras has said it plans to speed up efforts to sell oilfields, fertilizer, refining and other units to raise cash to pay down $130 billion of debt, the largest of any oil company.
Rio de Janeiro-based Petrobras has released little information about the assets it is selling. Gaspetro, whose sale was agreed last year, was the only major deal done so far and raised less than 4 percent of the total asset-sale goal.
The judge's ruling also blocks Mitsui from executing control over gas distribution activities related to the sale and orders Petrobras and Mitsui to turn over all sale-related documents within five days.
Mitsui declined to comment. Petrobras said it had not been informed of the decision and will take necessary legal action when it is. It said the sale was entirely legal.
The injunction against the sale is the second in two months. On Dec. 3, Brazil's state of Bahia won an injunction against the sale on concern that it may reduce its control of Bahiagas, a state-controlled natural gas utility.
Bahia withdrew its case just before Christmas after Petrobras and Mitsui assured the state of its continued control of Bahiagas. Gaspetro and Mitsui are both partners in Bahiagas.
$1 = 4.05 Brazilian reais Reporting by Jeb Blount and Marta Nogueira; Editing by Frances Kerry and Grant McCool