Two Scotland Yard officers are being investigated over their response to a firearms offence linked to the police shooting that sparked riots across the country.
The pair have been placed on restricted duties over the actions after allegations of an assault with the gun believed to have been later found at the scene where Mark Duggan was shot dead by police marksmen.
Sarah Green, Commissioner of the Independent Police Complaints Commission, said: "Our investigation will consider whether all investigative lines were promptly identified and acted upon by officers from the Metropolitan Police Service and to what extent, if any, the conduct of this investigation may have impacted on the supply of the firearm found at the scene of the shooting of Mark Duggan."
Unemployed Kevin Foster, 29, was charged on Wednesday over an assault and possession of a BBM Bruni Mod 92 handgun with intent to cause fear of violence at the Lagoon Hair Salon, in Hackney, east London, in July.
He will also appear at Waltham Forest Magistrates' Court next week charged with transferring or selling the firearm to another party.
A Scotland Yard spokesman said: "The Metropolitan Police Service has reviewed the original investigation conducted by two officers from Hackney borough into the actual bodily harm and possession of a firearm with intent incident that took place on 29 July in Kingsland Road, Hackney.
"Due to concerns about the quality of the investigative response the MPS has voluntarily referred the investigation to the Independent Police Complaints Commission.
"They have informed us that they will conduct an independent investigation. The MPS has put both officers on restricted duties pending the outcome of this investigation."
Ms Green added: "We have informed Mr Duggan's family of the situation today and IPCC family liaison managers continue to be on hand to support Mr Duggan's family while investigations continue."
Mr Duggan's death in Tottenham, north London, on August 4, was the trigger for the first of four nights of riots that spread from the capital across England. Initial reports that Mr Duggan shot at police were dismissed by ballistic tests which later found that a bullet which lodged itself in one officer's radio was police issue.