Britney Spears' attorney Mathew Rosengart has accused her former business manager of helping establish her 13-year conservatorship and receiving at least $18 million (£15 million) from it.

In court documents obtained by Variety and The Hollywood Reporter, Rosengart claims Tri Star Sports and Entertainment and co-founders Louise 'Lou' Taylor and Robin Greenhill, who served as Britney's business managers from 2008 to 2020, were directly involved in setting up the legal arrangement in February 2008.

"Contrary to Tri Star's public position and Ms. Greenhill's November 4, 2021 sworn Declaration in which she stated that 'in early 2008, Tri Star had no role in Ms. Spears' affairs,' Tri Star's own internal emails (obtained from a third-party) demonstrate that Tri Star's Lou Taylor played a substantial role in Ms. Spears's affairs prior to and in the early days of the conservatorship, 'in early 2008,'" the filing states.

"Tri Star, Lou Taylor and Robin Greenhill have all denied that Tri Star was involved in the creation of the Conservatorship, no doubt aware that such involvement - shortly after it extended the generous loan to Mr. (Jamie) Spears - would call into question not just the exorbitant fees paid to Tri Star over the years but also the motives for placing Ms. Spears into a 13-year conservatorship in the first place," he continued, claiming Tri Star made $18 million from Britney's estate.

Tri Star's attorney Scott Edelman issued a statement to both outlets insisting the allegations made in Rosengart's filing are "misleading".

"As all the evidence makes abundantly clear, the conservatorship was set up on the recommendation of legal counsel, not Tri Star, and approved by the Court for more than 12 years," Edelman said. "In fact, Tri Star was not even the business manager for the conservatorship when it was established. Cherry-picked excerpts from emails cannot change the facts, which is why this nonsense will all end once and for all when records are unsealed."

Rosengart has been trying to get Tri Star to comply with subpoenas for depositions, financial information and other documents as part of his investigation into the conservatorship, which was terminated in November.

Tri Star's lawyer filed a motion to quash his request, and Rosengart made the latest allegations in his response.