The civil servant head of Scotland Yard's watchdog is under investigation over allegations of racism.
Catherine Crawford, chief executive of the Metropolitan Police Authority (MPA), is at the centre of an independent inquiry.
It was sparked after members of the Metropolitan Black Police Association (MBPA) claimed she discriminated against ethnic minority officers.
They told investigator Anthony Allen she failed to hold senior members of the force to account over claims of racial and religious prejudice.
Mrs Crawford was a key behind-the-scenes figure in an angry race row which embroiled Britain's largest force last year.
The MPA, led by London Mayor Boris Johnson, is responsible for the appointment and discipline of senior officers.
Mrs Crawford has advised senior officers, including former Commissioner Sir Ian Blair, on how to handle a series of explosive claims against the force. Former Assistant Commissioner Tarique Ghaffur, Commander Ali Dizaei and Commander Shabir Hussain all alleged racism.
Legal documents submitted by the MBPA said members have been concerned for some time about the conduct of Mrs Crawford, a source confirmed. It is understood that further claims have been made that complaints against ethnic minority officers were probed more vigorously than those against white officers.
An MPA spokeswoman said: "A complaint against MPA chief executive Catherine Crawford has been received and formally recorded by the Authority's complaints officer.
"All complaints made against members of staff are taken seriously and the Authority has a formal process to deal with them. As this complaint is against the MPA chief executive, an independent investigating officer has been appointed."
