The Boy Scouts of America has locked away in its "perversion files" the names of 7,819 scout leaders who allegedly preyed on boys, a lawyer who is representing the sexual abuse victims claimed Tuesday.

The files, which go back to 1944, also include the names of 12,254 victims, said the lawyer, Jeff Anderson.

"Those are numbers that were not known before today or ever revealed by the Boy Scouts of America," Anderson told NBC News. "The scope of what was contained in the perversion files has dramatically expanded beyond what was known."

Anderson said the figures came from Dr. Janet Warren, a professor at the University of Virginia's medical school, who for five years had worked on a contract basis with the Scouts to evaluate how they handled sexual abuse within the organization from 1944 to 2016. She had access to review the files as part of her work. Warren revealed the figures in January while testifying in an unrelated child sex abuse case that took place at a Minnesota children's theater company, he said.

But while the Scouts have acknowledged keeping the files, they have so far resisted demands to release all of the names, Anderson said.

"They may have removed them from scouting, but the Boy Scouts of America have never alerted communities that this scout leader, this coach, this teacher is known to be a child molester," Anderson said. "That is the real alarming fact that needs to be mentioned today. It's systematic and across the country."

NBC News reached out to Warren for comment, but there was no immediate response.

A Boy Scout uniform in a store at the Marin Council of the Boy Scouts of America in July 2015 in San Rafael, California. Justin Sullivan / Getty Images file

In a statement, the Scouts apologized "to anyone who was harmed during their time in Scouting."

"At no time have we ever knowingly allowed a sexual predator to work with youth, and we mandate that all leaders, volunteers and staff members nationwide immediately report any abuse allegations to law enforcement," the statement said.

The Scouts said that all instances of suspected abuse are reported to law enforcement, that "all of the names on the 'Anderson List' are publicly available" and that "all of these individuals were removed from Scouting and reported to law enforcement."

The Scouts said that "decades ago" they had "adopted some of the strongest barriers to abuse" and that the safety and protection of the children were its "top priority."

Slammed by numerous lawsuits and facing mounting legal costs, the venerable nonprofit organization, which has been around for over a century, warned in December that it was considering filing for Chapter 11 protection.

“We have a social and moral responsibility to fairly compensate victims who suffered abuse during their time in Scouting, and we also have an obligation to carry out our mission to serve youth, families and local communities through our programs,” the chief scout executive, Michael Surbaugh, said in the statement at the time.

Anderson also said his law firm, using publicly available documents, including legal settlements and news accounts, had been able to compile a list of 130 former scout leaders in New York and 50 more in New Jersey who were removed from the organization and whose names appeared in the available "ineligible volunteer files" maintained by the Scouts.

Anderson released those names Tuesday at two news conferences.

Lawyer Jeff Anderson points to a legal document at a news conference accusing Boy Scouts of America of harboring thousands of sexual abusers in New York on Tuesday. Brendan McDermid / Reuters

NBC News and other news outlets first reported the existence of the "perversion files" in 2012, when the Scouts released 1,247 cases of known or suspected child abusers in response to a lawsuit by two Portland, Oregon, lawyers.

Those files detailed cases from 49 states from 1965 to 1985. And they revealed the hardball tactics that attorneys for the Scouts used to defend the organization, as well as the legal hurdles that scout sex abuse victims — like clergy sex abuse victims — faced when they tried to sue for damages.

Later, The Los Angeles Times released a database that tracked 1,900 cases of suspected scout sexual abusers spanning 1947 to 2005.

Anderson said he was convinced that there even more cases are in the files "that are being held and hoarded at the Boy Scouts of America headquarters." He said he intended to sue the Scouts on behalf of the victims to open up those files.

"I don't know how many of those people were ever charged with crimes," he said. "I don't know how many of them are still alive."

Anderson is best known for publicly releasing lists of Roman Catholic priests who have been credibly accused of sexual abuse.

Last month, he released a 185-page report that listed the names of hundreds of accused priests in Illinois, along with six nuns and a handful of lay people.

Anderson said his team used the same methods to pull together the list of priests that he used to compile the list of scoutmasters in New York and New Jersey.

His list includes two scout leaders who were accused of running what, according to a Nov. 15, 1983, article in The Star-Ledger newspaper of Newark, New Jersey, was alleged in court documents to be a "cult" involving at least 35 teenagers.