WASHINGTON — The government has filed a $25 billion settlement with the five largest mortgage lenders in federal court, putting an official stamp on the landmark agreement announced last month over alleged foreclosure abuses.

The court papers offered few new details on the deal between the federal government and 49 states and Bank of America, Wells Fargo, JPMorgan Chase, Citigroup and Ally Financial.

Meanwhile, U.S. Attorney Bill Nettles in Columbia announced a $95 million settlement with four of those mortgage servicers — excluding Ally. The banks agreed to the settlement — as part of the larger resolution — to address allegations of filing false Federal Housing Administration mortgage insurance claims.

Nettles said it is the largest false claims act settlement ever obtained by the district of South Carolina. The lawsuit was initially filed in Columbia by Florida resident and whistleblower Lynn Szymoniak. She will receive $18 million from the proceeds of the settlement, Nettles said.

“Whistleblowers play an important role in protecting taxpayer funds from fraud and abuse,” Nettles said in a statement. “Settlements like this one help maintain the integrity of the federal mortgage servicing process.”

Nettles said the agreement is the first step in holding mortgage servicers accountable for fraudulent and abusive practices in South Carolina and across the country.

Nettles has made this issue his top priority his past two years as the U.S. Attorney in Columbia.

“Our investigation is ongoing as we continue to ascertain the full magnitude of wrongdoing and to seek redress for the United States government,” he said.

Under the larger, $25 billion settlement, banks will pay roughly $20 billion to help borrowers avoid foreclosure. Most of that will go toward reducing loans for about 1 million of the 11 million U.S. households that owe more on their mortgages than their homes are worth.

The banks will also pay $5 billion in cash to the federal and state governments. Approximately a third of that money will go into a fund that be used for sending $2,000 checks to about 750,000 Americans who were improperly foreclosed upon from 2008 through 2011.

The banks will have to complete 75 percent of their loan relief requirements within two years and 100 percent within three years.

The banks didn’t admit wrongdoing as part of the settlement. Federal and state law-enforcement authorities could still pursue criminal action against them, the government says.

The settlement, reached after nearly a year and a half of contentious negotiations, is subject to the approval of a federal judge in Washington.

It is the largest settlement involving a single industry since the $206 billion multistate tobacco deal in 1998.

But consumer advocates have said far too few people will benefit. The deal applies only to privately-held mortgages and not to those owned by mortgage giants Fannie Mae and Freddie Mac. Banks own about half of all U.S. mortgages, or about 30 million loans; Fannie and Freddie own the other half.

The banks will be required to make foreclosure their last resort. They won’t be allowed to foreclose on a homeowner who is being considered for a loan modification. The new standards are aimed at preventing recent abuses by banks such as lost paperwork and so called robo-signing – the practice of employees signing papers they hadn’t read or using fake signatures to speed foreclosures.

About 75 percent of the settlement money will go to California and Florida, two of the states hardest hit by the housing crisis and the ones with the most underwater homeowners.

Staff writer Kristy Eppley Rupon contributed.