The New York Times reports: A British private detective at the center of the phone hacking scandal that has shaken Rupert Murdoch’s media empire cited the MI5 file of a close friend of Princes William and Harry in notes he kept on his work for the tabloid The News of the World, according to a suit filed in London.

But the court papers, released to The New York Times, do not clearly indicate whether the detective, Glenn Mulcaire, accessed the highly classified intelligence file directly, was told of its contents or was simply noting its existence.

The documents, dated Sept. 23, accuse Mr. Mulcaire and the now-closed News of the World of invading the privacy of Guy Pelly, a London nightclub owner and a confidant of the princes. The defendants, the suit says, hacked Mr. Pelly’s cellphone, set up an e-mail address in his name and flew him to Las Vegas on false pretenses to trick him into revealing details about his royal friends.

But the most intriguing accusation relates to at least two references to Mr. Pelly’s MI5 profile in Mr. Mulcaire’s detailed records. He kept copious notes covering his conversations with his employers at the tabloid, his sources, his methods and the information he gleaned.

One reference, the suit said, was in an electronic file titled “Project Guy W. Pelly,” which “included his mobile number, his parents’ landline number, his parents’ address and a further reference to the MI5 profile.”

Somewhat ambiguously, the suit states: “It is to be inferred that individuals close to members of the Royal Family have MI5 profiles and that this information was obtained unlawfully by the Defendants.”