Britney Spears' lawyer files new documents accusing Jamie Spears of privacy invasion

Jamie Spears (left) and Britney Spears at the Billboard Music Awards in Las Vegas on May 17, 2015. Photo/ AP.

Britney Spears' lawyer has filed legal documents accusing her father of having "engaged in horrifying and unconscionable invasions of his adult daughter's privacy".

Mathew Rosengart lodged documents with the Los Angeles Superior Court today in which he declared "the chickens have truly come home to roost" following a "bombshell exposé" by The New York Times, which claimed Jamie Spears had allegedly recorded his daughter's communications without her permission.

In a filing obtained by the New York Post's Page Six column, the lawyer stated: "Specifically, the Times reported that he and others 'ran an intense surveillance apparatus that monitored [Ms Spears's] communications' and also evidently captured attorney-client communications with her prior lawyer, which communications are a sacrosanct part of the legal system."

He also claimed that what was "even more shocking" was that Jamie - who is co-conservator of the 39-year-old pop star's affairs -" crossed unfathomable lines" by having allegedly illicitly "captured audio recordings from Britney's bedroom, including private communications with her children", which he branded a "disgraceful violation" of the Circus hitmaker's rights.

The lawyer told the outlet in a statement: "Unauthorised recording or monitoring of Britney's private communications — especially attorney-client communications, which are a sacrosanct part of the legal system — represent an unconscionable and disgraceful violation of her privacy rights and a striking example of the deprivation of her civil liberties.

He added, "Placing a listening device in Britney's bedroom would be particularly horrifying and corroborates so much of her compelling, poignant testimony. Mr Spears has crossed unfathomable lines."

The documents pointed out that Britney's home state of California is a "two-party" consent area, meaning both those doing the recording and those being recorded need to give authorisation.

And Mathew claimed the allegations will distract Jamie from acting in Britney's best interests, adding it to his arguments as to why he wants him removed as conservator by September 29, when a court hearing is due to take place.

He argued: "As a result of these deeply disturbing allegations, Mr Spears will inevitably be focused over the next several days and weeks on defending his own interests not his daughter's (yet again)."

Mathew - who has previously argued Jamie should be removed from his post because he could "impede" negotiations for Britney and her fiance Sam Asghari's prenuptial agreement, he has a poor financial history, and both his client's mom, Lynne Spears, and temporary conservator Jodi Montgomery also want him out - wants to question the Stronger singer's dad but expects he will invoke the Fifth Amendment right against self-incrimination.

He said in the filing: "Even assuming Mr Spears were to invoke the Fifth Amendment at his deposition, there are questions he still would be required to answer, which would inform the Court's decisions on these accounting and financial issues at an evidentiary hearing in the future.

"Relatedly, the mere invocation of the Fifth Amendment would be highly illuminating and would also permit the Court or jury to draw an adverse inference based upon that invocation."