Weeks before Jay-Z was publicly named in a lawsuit of raping an unnamed teenage girl alongside Sean “Diddy” Combs in 2000, the rap mogul born Shawn Carter received a letter from the plaintiff’s lawyer threatening to “immediately file” a “public lawsuit” against him unless he agreed to resolve the allegations through mediation for a financial payout, his lawyers have said.

Instead, his lawyers sued the lawyer behind the demand, Tony Buzbee, citing Jay-Z as a John Doe. Buzbee has filed at least 20 civil lawsuits, initially by anonymous plaintiffs, against Combs accusing him of sexual misconduct, and has used Instagram, a phone hotline and a news conference to find clients.

Lawyers for Jay-Z accused Buzbee of trying to “extort exorbitant sums” from him via false assault claims; they said they received letters about two clients, though only one has been filed, by the anonymous woman. “Plaintiff presently faces a gun to his head,” they wrote in the suit, filed on 18 November in Los Angeles.

“Either repeatedly pay an exorbitant sum of money to stop defendants from the wide publication of wildly false allegations of sexual assault that would subject Plaintiff to opprobrium and irreparably harm plaintiff’s reputation, family, career and livelihood, or else face the threat of an untold number of civil suits and financial and personal ruin.”

Jay-Z denies the allegations and has said “whomever would commit such a crime against a minor should be locked away”. Combs is in jail awaiting trial on federal sex trafficking and racketeering charges, and has denied the allegations.

Jay-Z is seeking to dismiss the case, claiming the court does not have jurisdiction over a lawsuit such as this.

His lawyer Alex Spiro asked the judge to expedite the hearing on the motion to dismiss, “due to the highly sensitive nature of this matter and the intense media scrutiny”.

Spiro described the case as “a shakedown. [Carter] is not mentioned, referenced, or implicated in any way in the criminal investigation of Mr Combs. He is neither a target nor a person of interest in that investigation.”

Lawyers for Jay-Z have also argued that the unnamed woman should file her complaint under her real name, claiming that there is insufficient reason for her to remain anonymous. “Mr Carter deserves to know the identity of the person who is effectively accusing him – in sensationalised, publicity-hunting fashion – of criminal conduct, demanding massive financial compensation, and tarnishing a reputation earned over decades,” wrote lawyer Spiro.

On 8 December, Buzbee amended the lawsuit to name Carter, previously described as a John Doe and “celebrity and public figure”, as accused of raping the girl with Combs in 2000, when she was 13.

A day later, lawyers for Jay-Z said that he was the John Doe behind the suit against Buzbee.

In a public statement, Jay-Z accused Buzbee of “blackmail”, said Buzbee had made “a terrible error in judgment” and lamented the effect of the allegations on his family with Beyoncé, particularly his oldest daughter, Blue Ivy, 12.

Buzbee responded accusing Jay-Z of “orchestrating a conspiracy of harassment” against him and other lawyers in his firm in an attempt to intimidate and silence his client.

On Monday, Buzbee told the New York Times that “sending a basic litigation demand letter” was not tantamount to extortion of blackmail, and had asked Jay-Z for a “confidential sit down” to protect the privacy of his client.

“We won’t get bogged down in a silly sideshow that tries to make the lawyers the focus of what are very serious allegations brought by a courageous woman,” Buzbee told the Times.