The recent admission by a major mortgage lender that it had filed dubious foreclosure documents is likely to fuel a furor against hasty foreclosures, which have prompted complaints nationwide since housing prices collapsed.

Lawyers for distressed homeowners and law enforcement officials in several states on Friday seized on revelations by GMAC Mortgage, the country’s fourth-largest home loan lender, that it had violated legal rules in its rush to file many foreclosures as quickly as possible.

Attorneys general in Iowa and North Carolina said they were beginning separate investigations of the lender, and the attorney general in California directed the company to suspend all foreclosures in that state until it “proves that it’s following the letter of the law.”

The federal government, which became the majority owner of GMAC after supplying $17 billion to prevent the lender’s failure, said Friday that it had told the company to clean up its act.