Freddie Mac, the troubled US mortgage agency trying to rebuild its reputation following an accounting scandal last year, is facing a fine and possible civil legal action after the US Securities & Exchange Commission said it might have violated federal securities laws.

The agency, which at the end of last year revealed it had understated earnings by more than $5bn (€4bn) between 2000 and 2002, said late on Wednesday it had received a "Wells Notice" from staff at the SEC.