Colorado's Attorney General John Suthers has sued two more law firms in the state for fraud, accusing them of inflating foreclosure costs charged to homeowners, his office said.

As part of an ongoing investigation, Suthers has filed eight civil law enforcement actions against Colorado foreclosure law firms in 2014, five of which resulted in settlements totaling nearly $12 million.

The firms targeted earlier this year included the state's two largest, which were accused of defrauding homeowners, investors and taxpayers by grossly hiking costs and padding bills with unauthorized expenses.

On Monday, Suthers' office named the latest two firms as Robert J. Hopp & Associates and The Hopp Law Firm, and The Vaden Law Firm, including the firms' principals and their affiliated title companies.

It said the Vaden firm is alleged to have inflated foreclosure costs for postings, court filings and titles, while Hopp is accused of routinely collecting between $1,200 and $1,400 in premiums for non-existent title insurance policies.

Calls to the Hopp law firm went unanswered, while Vaden did not immediately respond to a message seeking comment.

"For abusing the foreclosure process for their own profit, eight Colorado foreclosure law firms have now been targets of investigation by my office," Suthers said in a statement.

"It is my hope that these actions will result in greater transparency and fairness in the legal processing of foreclosures."

The focus on foreclosure expenses by Suthers' investigation mirrored a separate federal probe by Manhattan U.S. Attorney Preet Bharara's office.

In July, HSBC Holdings Plc agreed to pay $10 million to settle U.S. government charges that it defrauded taxpayers by submitting inflated bills to process residential foreclosures. At least six other banks have disclosed receiving subpoenas as part of the federal probe.