The majority of police forces in England and Wales allow trans-identifying biologically male officers to strip search women, research has revealed.
At least 34 out of 43 forces have either implemented the policy or intend to.
The research, conducted by the Women's Right Network, claimed police forces were pandering to vocal transgender lobbyists.
Police guidelines already ensure female officers are required to carry out intimate searches of a biological male suspect even if they identify as a woman.
A female police officer and an inset of Cathy Larkman
GETTY/SOUTH WALES POLICE
Officers can face disciplinary proceedings if they refuse.
Heather Binning, who founded the Women's Rights Network, said: "Self-identification is not UK law and women should not be paying the price for policing beyond the law.
"Police chiefs have failed us again. This is not reasonable or lawful and we do not consent.
"It is state-sanctioned sexual assault, and it must not be tolerated."
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Two female Metropolitan Police officers standing roadside in Trafalgar Square
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Retired police superintendent Cathy Larkman, who authored the WRN's State Sanctioned Sexual Assault report, claimed dozens of female officers had approached the group to raise their concerns.
However, Larkman also claimed there was a culture fear within the police that prevented them from speaking out.
A female police officer alleged she was threatened with disciplinary action when she questioned the policies.
She told The Daily Mail: "I fear both for my colleagues and for vulnerable suspects."
Retired police superintendent Cathy Larkman
SOUTH WALES POLICE
The officer added: "A strip search is a humiliating and potentially traumatic experience and everything should be done to ensure a suspect is treated with dignity and respect."
The report comes just two years after the National Police Chiefs' Council (NPCC) released advice saying: "Chief Officers are advised to recognise the status of transgender colleagues from the moment they transition."
An NPCC spokesman previously said: "All searches are dealt with on a case-by-case basis after consideration by a custody sergeant based on the response of the detainee.
"All searches are carried out in line with the officer or staff member's training and legal authority."