The FBI is investigating Fannie Mae, Freddie Mac, Lehman Brothers Holdings Inc and insurer American International Group Inc AIG and their senior executives for potential mortgage fraud, CNN reported on Tuesday. The FBI did not provide specifics but said the inquiries were part of a broader probe, CNN said.

The bureau is trying to determine whether anyone in those financial institutions, including their senior executives, had any responsibility for providing "misinformation," CNN reported.

"As part of our investigative responsibility, the FBI conducts corporate fraud investigations. The number of cases fluctuates over time, however we do not discuss which companies may or may not be the subject of an investigation," said Justice Department spokesman Brian Roehrkasse. A federal law enforcement official confirmed the FBI is now looking at 26 cases of potential corporate fraud related to the collapse of the US mortgage lending industry.