Metropolitan Police Commissioner Sir Ian Blair has publicly warned one of his most senior officers to step into line.
The New Scotland Yard head said he will hold a crunch meeting with Assistant Commissioner Tarique Ghaffur.
In a strongly-worded statement, Sir Ian defended his record on diversity as "occasionally blood-stained" but "always principled and persistent".
He was speaking after it emerged Mr Ghaffur is preparing an employment tribunal case against the Met with claims of racial discrimination.
Sir Ian said every member of his force must "work to my direction" or be dealt with "robustly and quickly".
Speaking at the Metropolitan Police Authority, he said any suggestion he would not speak to Mr Ghaffur was "complete nonsense".
He said: "I believe I have a long, honourable and occasionally blood-stained record on the championing of diversity - not perfect but always principled and persistent.
"That said, I have asked Tarique Ghaffur, in view of media reports, to come and see me.
"I hope that this will be resolved satisfactorily between us but will state here publicly that every member of the Met works to my direction and must meet my reasonable requirements.
"Any other position is impossible. If that does not occur, I will deal with the matter robustly and quickly. I look to the support of the Authority to that end."
