THE Metropolitan Police told staff to delete references about sex and race discrimination during a complaint made by one if its officers, an employment tribunal has found.
Firearms officer Carol Howard, from Purley, brought a claim of discrimination against the Met earlier this year.
The panel found the 35-year-old had been "singled out and targeted" by her superior.
While her complaint was being dealt with an officer was asked to delete references to race or sex in a report into discrimination, the tribunal said.
The Met said it was "disappointed" by the findings and that it was taking the judgement "very seriously".
The Central London Employment Tribunal found Ms Howard was "directly discriminated" against "on the grounds of sex and race" while working as an officer on the elite Diplomatic Protection Group (DPG) between January and October 2012.
It added that her complaints about "victimisation" were "well-founded" and that the Met had concluded there was no evidence without having conducted a proper investigation.
The tribunal said it was "very concerned" that a detective assessing Ms Howard's fitness to work complaint was asked to delete the records on discrimination from a report.
This was done, the panel found, "not because they were not supported by evidence, but because the claimant had brought a complaint of race and sex discrimination in the tribunal".
This might "mislead complainants and tribunals into believing that the [investigating officer] has not found any discrimination when in fact he or she has done so".
Ms Howard's superior at DPG, which protects foreign embassies in London, was acting Inspector Dave Kelly who believed she was "dishonest and not up to the standard required" after several short periods of sickness. The panel found there was no "credible basis" for forming such a view.
Insp Kelly openly challenged her commitment in front of colleagues, asked them to ask "wholly inappropriate" questions about her personal relationships and blocked her requests to move to another unit.
Her lawyer, Kiran Daurka, from Slater & Gordon, said Ms Howard would seek compensation from the Met and called for the force's equality procedures to be completely rewritten.
She said: "This judgement is a damning indictment on the Met.
"The conduct of the Metropolitan Police and some of its senior officers towards Carol Howard was deplorable over the last two years.
"My client was subjected to discriminatory treatment because she is black and she is a woman."
In a statement the Met said: "We are very disappointed by the decision of the tribunal. We take the judgement very seriously and are naturally concerned about it.
"We will review the findings, take legal advice and take forward any learning or actions as appropriate."
