Government-controlled mortgage financer Freddie Mac has failed to promptly resolve serious consumer complaints that could involve possible fraud or improper foreclosures, a federal watchdog said on Thursday.

Freddie Mac and its larger sibling Fannie Mae pay mortgage servicers to collect loan payments and interact with consumers. Those servicers deal with a range of issues, including late fees and providing loan assistance and foreclosure alternatives to homeowners.

The Federal Housing Finance Agency Office of the Inspector General made an in depth examination of how the FHFA might have mishandled consumer complaints filed against the government-sponsored enterprises, including issues related to possible foreclosure actions.

As part of that audit, the FHFA's inspector general also took a closer look at Freddie Mac, which owns or guarantees more than 10.6 million residential mortgages worth about $1.6 trillion.

More than 34,000 escalated cases - which could involve servicing fraud or regulatory violations — were filed by homeowners with Freddie Mac and its eight largest mortgage servicers during a 14-month period between October 2011 and November 2012. But Freddie and its regulator have not resolved many of the cases, the audit found.

Although current FHFA guidelines require servicers to report the escalated cases they receive and resolve them within 30 days, more than 20 percent were not taken care of within that time frame, the audit found.

"Freddie Mac's oversight of servicer compliance has been inadequate," the audit report said. "Strengthened oversight — through actions aimed specifically at improving servicer compliance with escalated case requirements — can benefit homeowners, Freddie Mac, and taxpayers."

The watchdog recommended a number of ways to enhance the oversight of mortgage servicers and improve the oversight of Freddie Mac, including levying fines for servicers if they are late in responding to escalated cases.

In a letter to the watchdog responding to the audit, the FHFA said it agrees with "the intent of these recommendations," yet many of them would be limited due to new mortgage servicing rules announced in January by the Consumer Financial Protection Bureau.

The regulator said it will work with both Fannie Mae and Freddie Mac on new rules and try to ensure more timely responses to complaints.

Among Freddie Mac's eight largest servicers, which handled nearly 70 percent of the company's 10.6 million mortgages, four did not report any escalated cases, despite handling thousands such cases during the 14-month period audited by the watchdog.

Bank of America Corp., CitiMortgage, Provident and Wells Fargo & Co. did not comply, the watchdog said. Those servicers "did not report any escalated cases to Freddie Mac despite handling more than 20,000 such cases," the audit report said.

However, when contacted by the inspector general in connection with the audit, the four servicers said they would begin reporting to Freddie Mac.

Data on all of Freddie Mac's servicers revealed that about 98 percent never reported any escalated cases as of December 2012, the report stated.

Many of the servicers also manage loans for Fannie Mae.

Rep. Elijah Cummings, the top Democrat on the House Oversight Committee, said in a statement that the audit's findings represent "a sorry string of failures by FHFA leadership to protect American homeowners."

Cummings has been a leading lawmaker applying pressure on the regulator.