Federal prosecutors on Tuesday filed a civil mortgage fraud lawsuit against Deutsche Bank and its MortgageIT unit, accusing the bank of “reckless lending practices.”

The complaint, filed in United States District Court in Manhattan, contends that the bank and its subsidiary “repeatedly lied to be included in a government program to select mortgages for insurance by the government.”

“Once in that program, they recklessly selected mortgages that violated program rules in blatant disregard of whether borrowers could make mortgage payments. While Deutsche Bank and MortgageIT profited from the resale of these government-issued mortgages, thousands of American homeowners have faced default and eviction.”

The complaint seeks treble damages and penalties under the False Claims Act, which could amount to more than $1 billion.

“We believe the claims against MortgageIT and Deutsche Bank are unreasonable and unfair, and we intend to defend against the action vigorously,” a bank spokeswoman said in an e-mail statement.

Shares of Deutsche Bank tumbled in Frankfurt following word of the complaint.

Prosecutors allege that Deutsche Bank and MortgageIT “repeatedly lied” in order to participate in a Federal Housing Administration program that insures mortgages.

Related Links The complaint

Lenders in the program are required to have a quality control plan and resources, and are “entrusted with safeguarding the public from taking on risks that exceed statutory and regulatory limits.”

But the complaint says MortgageIT underwriters falsely certified that they had performed the required due diligence on the mortgages they endorsed.

In one instance cited in the complaint, an outside vendor was hired in 2004 to conduct quality control reviews of closed F.H.A.-insured loans. The vendor prepared letters detailing the underwriting violations it found. But no one at MortgageIT read the letters, the complaint says. Instead, the letters were stuffed, unopened, in a closet in the company’s Manhattan headquarters.

Between 1999 and 2009, MortgageIT endorsed more than 39,000 mortgages for F.H.A. insurance, totaling more than $5 billion in underlying principal obligations, the complaint says.

MortgageIT mortgages accounted for more than $386 million in F.H.A. insurance claims and costs.

Deutsche Bank acquired MortgageIT for $429 million in July 2006.

The United States attorney in Manhattan, Preet Bharara, has scheduled a news conference for 1 p.m. on Tuesday.

U.S. v. Deutsche Bank and MortgageIT