RIO DE JANEIRO, May 20 (Reuters) - Brazilian state-run oil company Petroleo Brasileiro SA said on Wednesday it will only be required to pay for excess oil rights found in areas it bought from the government in 2010 when it declares the fields commercially viable.
That means there is no set date for the conclusion of talks with the government on how to price any oil rights beyond the 5 billion barrels already purchased, Petrobras, as the company is known, said in a securities filing.
Investors are concerned that Petrobras, which many believe overpaid for the initial exploration rights in a September 2010 oil-for-stock swap, will be forced to pay more even as rising debt, delayed output and falling oil prices crimp its cash and force investment cutbacks.
Petrobras' preferred shares, the company's most traded class of stock, fell 6.3 percent on Tuesday, its biggest one-day decline in 3-1/2 months, on concern Brazilian Finance Minister Joaquim Levy was pressuring it to make the payment this year.
Local news agency Agencia Estado on Tuesday said that payment could be as high as 20 billion reais ($6.6 billion). A Petrobras representative declined to comment on the potential value of the payment.
A final determination of the fee Petrobras will have to pay for any discoveries above a level of 5 billion barrels will also be made only after volumes in the commercial fields are certified and reviewed by Brazil's oil regulator, the ANP, Petrobras said.
$1 = 3.03 Brazilian reais Reporting by Jeb Blount; Editing by Paul Simao