Geithner said the Treasury Department's Financial Crimes Enforcement Network had sent out an advisory to financial institutions asking for reports of financial activity that raises a "red flag" suggesting a possible mortgage scam.
The department also has set up a working group with federal and state law enforcement officials to coordinate the investigation of mortgage scams, he said.
Holder said his office won convictions against defendants in Kansas who "solicited homeowners going through foreclosure, told them that for a fee they could help them keep their homes and then filed fraudulent bankruptcy petitions on their behalf."
Another company in Brooklyn, N.Y., he said, set up straw buyers to acquire people's homes with a promise that the original owners would eventually get them back when the mortgages were restructured. That never happened, he said, and his office won convictions in that case as well.
Officials said homeowners looking for help should visit MakingHomeAffordable.gov, a website that has information on the administration's $75-billion effort to help homeowners out of mortgage trouble. It includes a link to a listing of HUD-approved mortgage counselors.
Homeowners also can call (888) 995-HOPE if they suspect a company is perpetrating a scam.