NEW YORK (REUTERS) - Ghislaine Maxwell, the British socialite fighting US federal sex trafficking charges, remains subjected to raw sewage, water deprivation, "hyper-surveillance" by overbearing guards and other unacceptable treatment in jail, according to her lawyer.

Maxwell, 59, is preparing for a possible November trial on charges she procured four underage girls for the late financier Jeffrey Epstein to sexually abuse. Maxwell has pleaded not guilty and faces up to 80 years in prison if convicted.

In a Tuesday night filing, lawyer Bobbi Sternheim said Maxwell was forced to change cells at the Metropolitan Detention Centre in Brooklyn after raw sewage last week permeated her cell.

Sternheim also said guards are still able to read Maxwell's confidential legal papers and monitor her meetings with lawyers, and that neither Maxwell nor her lawyers were allowed water during a four-hour meeting on Sunday.

Despite complaints about Maxwell's treatment, "little if anything has been done," Sternheim wrote.

"The ever-changing rules are negatively impacting Ms Maxwell's ability to prepare for trial," Sternheim added.

"The hyper-surveillance of Ms Maxwell and counsel during legal visits is highly inappropriate and invasive."

Sternheim's letter was in response to a June 7 letter from prosecutors that said guards can see but cannot hear Maxwell's discussions with the lawyers.

Prosecutors also said Maxwell still gets more time than any other inmate at the Brooklyn jail to use a computer and review evidence, and at least as much time to talk with her lawyers.

They also said Maxwell remains "physically healthy."

The office of US Attorney Audrey Strauss in Manhattan declined to comment on Sternheim's letter. The letter from prosecutors was made public on Wednesday.

Maxwell is the daughter of the late British publishing magnate Robert Maxwell, and a former girlfriend and longtime associate of Epstein.

She has been denied bail three times by US District Judge Alison Nathan, who oversees the case, and twice by a federal appeals court.

Epstein killed himself in a Manhattan jail in August 2019 after pleading not guilty to sex trafficking charges. New York City's medical examiner called the death a suicide.