The Tasering of the father of rapper Wretch 32 will be assessed by the police watchdog after the Met was instructed to refer it.
The rapper posted a video on Twitter of Millard Scott falling downstairs after he was being Tasered by officers in Haringey, in north London.
The force previously said that a review had found that “no indication of misconduct”.
But the Independent Office for Police Conduct (IOPC) used its powers to require the force to refer it.
A spokesperson for the force said that officers went to the property as part of “a long-running operation to tackle drugs supply linked to serious violence”.
After which, the Mayor of London, Sadiq Khan then called for an urgent investigation by the IOPC.
Describing the incident as “distressing”, he said: “It is absolutely vital that our police service retains the trust of the communities it serves”.
Scotland Yard later said that it would not refer the incident to the IOPC.
Wretch 32, whose real name is Jermaine Scott, shared the 36-second clip on his Twitter account with the caption: ‘This is how the police think they can treat a 62 year old Black man in Tottenham but this 1 happens to be my dad’.
It shows Mr Scott falling down the stairs after an officer is heard to warn: “Police officer with a Taser. Stay where you are”.
As officers ask if he is OK and tells him to keep still, a distressed woman can be heard to say: “They’ve Tasered him”.
Mr Scott said that he was “lucky to be alive”.
He said: “The only people who have invaded our space are the Metropolitan Police.
“The only people who seem to ignore the guidelines put out there are the Metropolitan Police.
“It seems at the moment in time that we are being singled out and targeted.