Brazil's state-owned oil company says it has received a subpoena from the U.S. Securities and Exchange Commission asking for documents tied to the investigation of Petrobras, which has been engulfed by corruption allegations.

In a statement sent Monday night, Petrobras said the SEC had requested documents "related to an investigation into the company." It said the documents would be forwarded to the SEC after consulting with U.S. and Brazilian law firms hired to conduct an independent internal investigation.

Authorities allege that top Petrobras executives operated a kickback scheme on contracts involving several billion dollars, with the money eventually being fed back to the governing Workers Party and other top parties for political campaigns.

Shares of the energy giant are traded on the New York Stock Exchange.