Met Commissioner Sir Paul Stephenson will discuss the patrols on Thursday
Armed police patrols have been introduced in London without authorisation, a police watchdog said.
Armed officers from the CO19 unit have begun pilot patrols in Tottenham - where three Turkish men died in a drug war - as well as Brixton and Haringey.
Metropolitan Police Authority (MPA) member Jenny Jones said it did not authorise the "change in tactics".
Met Commissioner Sir Paul Stephenson said there is no intention to introduce "routine" armed foot patrols.
The MPA will question the commissioner about the patrols in a City Hall meeting on Thursday.
Pilot patrols of armed officers have taken place in London estates since June.
The Metropolitan Police said it was a temporary response to a 17% rise in gun crime over the past six months.
But the MPA, which oversees policing in London, says the armed patrols can intimidate residents and could provoke an arms race with criminals.
MPA member Ms Jones said: "Even if you agree with routine armed patrols, and most people do not, everybody will be concerned that a change in tactics has been done without any authorisation from the management board."
She added: "Any police authority should think twice about this."
Joanne McCartney, Labour's policing spokesman on the London Assembly, described the armed patrols as a "step change" in policing.
She said: "We want these patrols to be halted until there has been a proper debate. I do not believe that armed patrols are necessarily the answer."
London Mayor Boris Johnson, who heads the MPA, said armed police have an important role to play but that they should be "the exception, not the norm".
Sir Paul Stephenson said: "There have not been any routine armed foot patrols, and nor will there be any."
He added: "Fewer than 10 intelligence-led specific operations have been undertaken by C019 which involved providing back up to neighbourhood teams.
"These were pre-planned operations, with specific objectives and timescales and were by no means routine in any way."
Sir Paul said firearms officers would continue to be deployed "in situations where firearms present a threat and in support of their unarmed colleagues as has always been the case".
He added: "If in the future it becomes necessary to extend uniformed armed deployments I will of course ensure full and robust consultation with the police authority and the wider community prior to implementation."