Britney Spears claims her father took $53 million during 13-year conservatorship

More allegations against Britney Spears's father have been revealed. Photo / Supplied

Britney Spears's father Jamie took $36 million (NZ$53m) during her conservatorship, new legal documents have revealed- and her lawyer hopes that she will get $6m (NZ$8.8m) back.

Documents obtained by TMZ reveal claims from Britney's lawyer that her father mismanaged business and finances throughout her 13-year conservatorship, which ended last November.

He goes on to claim that Jamie earned $8m that he did not have the right to, and hopes that a judge will order him to pay the sum back to Britney.

The pop star's father is said to have spent part of the money pitching a programme called Cookin' Cruzin' & Chaos. And it's claimed that "millions" more was spent on lawyers for the conservatorship, totalling more than $44m.

It comes after Britney issued a cease and desist letter to her sister Jamie Lynn Spears, who recently released a book called Things I Should Have Said in which she makes several claims about her sister.

The cease and desist letter reads: "The last thing Britney wants is to bring more attention to your ill-timed book and its misleading or outrageous claims about her.

"Although Britney has not read and does not intend to read your book, she and millions of her fans were shocked to see how you have exploited her for monetary gain. She will not tolerate it, nor should she."

The letter further claims that Britney faced "abuse and wrongdoing" during her conservatorship and will "no longer be bullied by her father or anyone else".

Britney has sent a cease and desist letter to her sister Jamie Lynn. Photo / Getty Images

Sources close to Jamie Lynn told TMZ she had not yet received the letter.

It comes amid a former FBI agent's claims that Jamie Spears "spied on" his daughter throughout the conservatorship, also according to legal documents filed by her lawyer Mathew Rosengart.

Rosengart filed a declaration on her behalf from former agent Sherine Ebadi who claimed that Jamie told Black Box Security to "place a secret recording device in Ms Spears's bedroom", E! News reported.

Britney's attorneys hired the former FBI agent, who currently manages forensic investigations at a private firm, to look into allegations from a former security company who looked after the pop star.

Following the investigation, Ebadi backed up the claims that Jamie Spears had a listening device secretly planted in his daughter's bedroom.