A human rights watchdog is to investigate the Met Police after it emerged references to discrimination were deleted from internal reports.
The inquiry by the Equality and Human Rights Commission (EHRC) comes after PC Carol Howard won a discrimination case against the force.
A tribunal found the firearms officer was discriminated against on the grounds of sex and race.
The Met said it welcomed the inquiry to "improve" its grievance procedures.
In July, a tribunal panel found the Met had "directly discriminated" against PC Howard between 31 January and 29 October 2012.
The officer still works for the force.
During the hearing, the panel was told that an internal report supporting her claims of sex and race discrimination had been deliberately rewritten ahead of the tribunal.
Mark Hammond, chief executive of the EHRC, said: "This independent and transparent investigation will establish whether the Met's procedures for handling employees' complaints about discrimination comply with the law."
The Commission said it will carry out an inquiry into claims of "unlawful discrimination, harassment and victimisation of employees by the Metropolitan Police".
Craig Mackey, deputy commissioner of Scotland Yard, said: "We had announced previously that we accepted the employment tribunal's findings and that we would be seeking an independent review and recommendations to improve our internal grievance procedures.
"The employment tribunal highlighted weaknesses in our existing system. We are determined to ensure that these are rectified as quickly as possible."
In a separate development, it has been announced that PC Howard will face no further action after she was arrested by another force.
Sussex Police, who did not name the officer, said a woman who was arrested on suspicion of harassment, making threats to damage property in Crawley, Sussex, perverting the course of justice, witness intimidation and possession of an indecent image of a child under 16, has been advised that there will be no further action taken against her.
The firearms officer was arrested twice by Sussex Police after a disagreement with her estranged partner and was also held by the Met Police in April this year, but had already been told that no further action would be taken by her employer.