BRAZIL (From news reports) -- Brazilian federal prosecutors asked a court on Monday to reimpose preventive measures against two key suspects in a corruption probe dubbed Operation Greenfield, which is investigating fraud at state-run companies' pension funds.

According to the prosecutors' statement, defendants Joesley Batista, from the family that controls meatpacker JBS SA , and José Carlos Grubisich Filho, chief executive of pulp producer Eldorado Brasil Celulose SA, breached an agreement that had been signed with the prosecutors related to the investigation.

Asking the court to recognize that the defendants "violated principles of good faith" contained in the agreement, the prosecutors petitioned a judge to block assets worth as much as 3.8 billion reais ($1.22 billion) belonging to the investigated parties.

The prosecutors said the sum would serve as "a guarantee" to compensate losses allegedly caused by the defendants in their business dealings with state-run companies' pension funds, as well as state-bank Caixa Econômica Federal and the FGTS workers' severance fund.

The probe of the pension funds is one in a string of corruption investigations into the vast overlap of Brazilian business and politics.

J&F, the Batista family holding company that controls both JBS and Eldorado, said it was "surprised" by the prosecutors' petition concerning both executives, calling their allegations "baseless and irresponsible."

Referring to Eldorado specifically, J&F said in a statement that all actions taken by the management and the board of the pulp producer were legal, communicated in a transparent manner and made in accordance with the company's bylaws.

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