Warnings of racism at Scotland Yard have fallen on "deaf ears" for more than a decade, a top policeman said as eight officers were suspended from the force.
Superintendent Leroy Logan, of the Black Police Association, said he was "disappointed" by the Met's apparent failure to take effective action following years of feedback from black communities.
He spoke after 10 complaints - relating to 20 officers and one member of police staff - were referred to the police watchdog, the Press Association reported.
The referrals came just days after Scotland Yard vowed to get to the bottom of "very damaging" footage of one officer apparently racially abusing a man and another allegedly assaulting a teenage boy last summer.
Supt Logan, a founder member and former chairman of both the London and National Black Police Association (NBPA), said while race relations had improved since a 1999 report accused the force of institutional racism, there had been a recent deterioration in attitudes.
Citing a need to "root out the bad boy cops," he said race relations had dropped down the agenda.
But he said the issue had been raised yearly by youths on the NBPA's community engagement programme.
"Every year since 2001, the young people have been saying how they believe they are being dealt with disrespectfully, not shown enough dignity, casual racist comments were being used," he said.
"We were telling the Met Police, some two or three commissioners back, this is what is coming up.
"But like so many things, it lands on deaf ears until such a time as a free press - the media - get hold of it and forces people into action."
The officer, who has more than 30 years of practical policing experience, added: "You would think these casual racist comments would be long gone and here we are and they are still coming up."
And he said the force now needed to "get its act together".
"The police service isn't in a good place," he added.
"Sometimes it's one step forward and two steps back. We see spikes of improvement but we definitely saw a dive in performance in terms of racial issues which went off the agenda.
"The issues haven't been reviewed effectively by external agencies, that's why we are getting these incidents. Race needs to be back on the agenda."
However he expressed faith in the force's ability to address the most recent crisis.
"I'm disappointed but I'm not discouraged," he said.
"We have to keep going because it is the legacy of our children we are looking at."
In total, eight officers and one member of staff at the Yard have been suspended.
Pc Alex MacFarlane has been temporarily stripped of his duties after a recording was made of a suspect being called a "n*****".
The arrested man, named as Mauro Demetrio, 21, from Beckton, east London, was arrested on suspicion of drug driving but no action was later taken. He recorded the abuse on his mobile phone.
It emerged that another officer, reportedly with Pc MacFarlane when Mr Demetrio was abused, was also placed on restricted duties after allegedly being seen kicking a 15-year-old black boy to the ground and kneeing him.
The incident was said to have happened in the custody area of an east London police station, with part of it apparently recorded on CCTV.
The Met is now working with the Independent Police Complaints Commission (IPCC) to investigate the string of allegations which include the bullying of PCSOs by a number of police officers and staff over an 18-month period in Wandsworth; an assault involving five officers from the Territorial Support Group against several youngsters in Hyde Park last year; and racist language by a Pc working in Westminster and by another Pc in Islington.
Elsewhere, four police officers have been temporarily stripped of their duties in Northern Ireland following the discovery of racist and sectarian text messages.
Yvette Cooper, shadow home secretary and minister for women & equalities, said: "These allegations must be taken extremely seriously by the Metropolitan Police Service, the Crown Prosecution Service and the IPCC.
"The police must ensure there is zero tolerance of racism in their ranks, and must act fast to deal with any suggestion of racism that arises. It is vital for justice that everyone from every community can be confident in the impartiality of the police and their ability to enforce the law fairly.
"The MPS worked hard to change after the Macpherson inquiry, but the number of these claims now is a very serious concern."