As expected, KPMG flung some mud of its own back at home mortgage giant Fannie Mae last week, accusing the government-subsidized company of breach of contract and fraudulent misrepresentation -- claiming that the problems leading to Fannie Mae’s $6.3 billion restatement were largely of the mortgage lender’s own making.

“Fannie Mae repeatedly and intentionally violated” its contractual obligations toward KPMG “by failing to disclose information to KPMG that was vital to KPMG's ability to perform audits and quarterly reviews and by misrepresenting material information,” Bloomberg News reported the accounting firm claiming in its federal district court filing. “Fannie Mae repeatedly, systematically and intentionally misled KPMG.”

Fannie Mae filed its own lawsuit in December, claiming that the Big Four firm committed malpractice when it gave clean audit opinions for financial statements from 1998 until 2004 that contained errors. Fannie Mae is trying to recover more than $2 billion from KPMG in damages, half of which is to cover the more than $1 billion Fannie Mae spent redoing its books.

KPMG served as Fannie Mae's auditor for 35 years, before being fired in 2004 as the mortgage lender’s problems came to light.

Both firms have been sued by investors, and in the most recent court filing, KPMG also disclosed that it has become the subject of regulatory inquiries. Last year the Securities and Exchange Commission accused Fannie Mae of fraud, eventually settling the charges after Fannie paid $400 million.