An amended lawsuit filed in federal court on Sunday alleges that rap moguls Jay-Z and Sean “Diddy” Combs raped a 13-year-old girl during a party in 2000.

Jay-Z denied the allegations on social media and lambasted the lawsuit, calling it part of a “blackmail attempt” by the plaintiff’s lawyer. In a statement posted by his label, Roc Nation, he said he was heartbroken for his family, and for having to explain the nature of the allegations to his and Beyoncé’s oldest daughter, Blue Ivy, 12. Lawyers for Jay-Z did not immediately respond to a request for comment by Reuters.

Combs denied all allegations against him, including this one, in October. He is in jail on federal sex trafficking charges, to which he has pleaded not guilty.

The lawsuit was filed originally in October in the Southern District of New York and at that time did not name Jay-Z as a defendant, though the amended lawsuit says that Jay-Z was identified as “Celebrity A” on the original complaint.

The lawsuit alleges that the unnamed girl was drugged and raped by both Jay-Z and Combs at a party hosted by Combs after the MTV music awards in 2000, which were held in New York.

She said that Jay-Z and Combs took turns raping her at the party, and that she drank a drink that made her feel “woozy and lightheaded”. She escaped, she said, by hitting Combs in the neck as he assaulted her, then ran to a petrol station and was collected by her father.

Tony Buzbee, the Texas lawyer representing the girl who filed Sunday’s lawsuit, has filed at least 20 civil lawsuits against Combs accusing him of sexual misconduct, and has used Instagram, a phone hotline and a news conference to find clients.

All of his suits have initially been filed by anonymous plaintiffs. A judge will determine whether the plaintiff in this suit can proceed without revealing her identity.

In his statement, Jay-Z said: “These allegations are so heinous in nature that I implore you to file a criminal complaint, not a civil one!! Whomever would commit such a crime against a minor should be locked away, would you not agree? These alleged victims would deserve real justice if that were the case. This lawyer, who I have done a bit of research on, seems to have a pattern of these type of theatrics!”

In an email to Reuters, Buzbee said the Jay-Z lawsuit “speaks for itself”.

“This is a very serious matter that will be litigated in court,” Buzbee wrote.

Buzbee, in his amended lawsuit, says his law firm had previously sent Jay-Z a letter seeking to mediate a settlement.

Jay-Z, the lawsuit says, responded to that letter by filing a lawsuit against Buzbee, and by “orchestrating a conspiracy of harassment” against Buzbee and other lawyers in his firm, which the lawyer said was an intimidation tactic meant to silence his client.

In a post on social media, Buzbee said the alleged rape victim he was representing “never demanded a penny” from Jay-Z, writing that “she only sought a confidential mediation”.

Buzbee last week filed a lawsuit against the law firm Quinn Emanuel Urquhart & Sullivan, whose lawyers represent Combs and Jay-Z, accusing the firm’s legal team of harassing his colleagues, his clients and his family.

Quinn Emanuel Urquhart & Sullivan did not respond to requests for comment from Reuters.

Jay-Z’s statement concluded by expressing his support to “true victims in the world, who have to watch how their life story is dressed in costume for profitability by this ambulance chaser in a cheap suit”.

He said Buzbee had made “a terrible error in judgement” in assuming all celebrities were the same. “I’m not from your world. I’m a young man who made it out of the project of Brooklyn. We don’t play these types of games. We have very strict codes and honour.

“We protect children, you seem to exploit people for personal gain. Only your network of conspiracy theorists, fake physics, will believe the idiotic claims you have levied against me that, if not for the seriousness surrounding harm to kids, would be laughable. I look forward to showing you just how different I am.”

Combs was recently denied bail for a third time by a judge in New York City who described him as a “serious risk” for witness tampering. Prosecutors have previously accused Combs of trying to contact prospective witnesses from jail and to create “narratives” to influence public opinion and potential jurors for his impending sex trafficking trial.