A new lawsuit against the Boy Scouts of America charges that there are hundreds of previously unreported cases of sexual abuse in the organization.

The suit, filed Monday in Philadelphia’s Court of Common Pleas, says that lawyers for the Abused in Scouting group have identified 350 alleged abusers who do not appear in the Boy Scouts’ ineligible volunteer files, the Washington Post reported.

Those include the alleged abuser of the suit’s plaintiff, who is only identified as 57-year-old S.D. in court documents.

The accuser alleges that he was assaulted “hundreds” of times by a Scout leader in Pennsylvania over a four-year period in the 1970s.

The suit claims the alleged abuse would not have been possible had it not been for the negligence of the Boy Scouts, which engaged in “reckless misconduct” when it failed to protect participants and purposely tried to keep sexual assault incidents hidden, according to the news outlet.

“BSA knew for decades that sexual predators of boys had infiltrated scouting,” the suit says, claiming that the Boy Scouts “knew or should have known the dangers” that the alleged pedophiles posed, according to the Washington Post.

S.D. claims in the lawsuit that starting in about 1974 or 1975 while he was 12 or 13 years old, he was preyed upon by an assistant scoutmaster who “actively groomed young boys under his charge for later sexual molestation.”

The alleged victim says he went through “hundreds of instances of fondling, hundreds of incidents of oral sexual assault and repeated attempts of anal penetration” at Camp Acahela — a Boy Scout retreat in Pennsylvania — and at his accuser’s home, according to the suit.

The plaintiff’s lawyer and one of the lead lawyers of Abused in Scouting, Stewart Eisenberg, told the Washington Post that his client “had tremendous effects from the abuse.”

“This is the first time he’s ever come forward,” Eisenberg said. “He’s held it in for all those years.”

According to the report, lawyers for Abused in Scouting have recently gathered hundreds of allegations from men — and at least one teen — from around the country who claim they were assaulted or harassed during their time in the Boy Scouts.

The allegations have been forwarded to the Boy Scouts with the accusers’ names redacted, Tim Kosnoff of Abused in Scouting told the Washington Post.

The Boy Scouts said in a statement to the news outlet that it has made 120 reports to law enforcement based on the information from the Abused in Scouting group.

“We care deeply about all victims of abuse and sincerely apologize to anyone who was harmed during their time in Scouting,” the organization said. “We believe victims, we support them, we pay for counseling by a provider of their choice, and we encourage them to come forward.”

“The BSA has taken significant steps over many years to ensure that we respond aggressively and effectively to reports of sexual abuse,” the statement read. “We recognize, however, that there were instances in our organization’s history when cases were not addressed or handled in a manner consistent with our commitment to protect Scouts, the values of our organization, and the procedures we have in place today.”