SAO PAULO (Reuters) - Oil rig producer Sete Brasil Participações SA said on Friday that British lender Standard Chartered Plc (>> Standard Chartered PLC) is seeking early repayment of a loan, as fallout from a corruption scandal involving the Brazilian firm's main client cuts access to fresh financing.

Standard Chartered made a formal request to Fundo Garantidor da Construção Naval, or FGCN, to trigger guarantees on the loan, Sete Brasil said in a statement. FGCN, which provides protection to banks from potential defaults by shipbuilding firms, has 30 business days to study the request, the statement added.

A source with knowledge of the matter told Reuters earlier in the day that the loan, which was worth between $200 million (133 million pounds) and $300 million, was one of many deals in which foreign banks helped fund Sete Brasil's rig-building plans. In 2013, Standard Chartered teamed up with Japanese, Canadian, U.S. and Brazilian lenders to extend $1.25 billion in fresh credit to Sete Brasil.

When Sete Brasil was founded in 2011, it pledged to spend more than $25 billion to build as many as 29 deep-water drilling platforms that would be leased to state-controlled oil producer Petróleo Brasileiro SA. Petrobras (>> Petroleo Brasileiro Petrobras SA), as Sete Brazil's main client is called, is engulfed in a corruption scandal involving key contractors, which has paralysed rig and equipment purchases.

London-based Standard Chartered and FGCN, which is run by state lender Caixa Econômica Federal, had no immediate comment.

Rio de Janeiro-based Sete Brasil, founded by Petrobras and banks including Grupo BTG Pactual SA (>> Grupo BTG Pactual), is faced with a chronic cash-flow shortage as Petrobras has delayed payments and borrowing costs have risen. The company faces 11 billion reais in debt repayments next month and creditors are reluctant to roll over its debt.

Another source told Reuters in January that state lenders BNDES and Banco do Brasil SA (>> Banco do Brasil SA) were in talks to disburse more than 4 billion reais ($1.2 billion) in bridge loans to Sete Brasil. But the lifesaving loan could fall through after a former Petrobras and Sete Brasil executive admitted accepting bribes in exchange for contracts, the source noted.

"Sete Brasil is confident that it will find a solution to getting long-term financing, which was contemplated since its inception ... so the lender reverses its decision," the statement added.

(Reporting by Guillermo Parra-Bernal, additional reporting by Priscila Jordão in São Paulo; editing by Jeffrey Benkoe, Matthew Lewis and Christian Plumb)