A large number of Met police Counter Terrorism Firearms Officer have stepped back from armed duties, with the exception of five officers who are on annual leave, GB News has been told.
In a worsening crisis around armed policing, almost all Armed Response Vehicles in the Capital have also opted for a "period of reflection" and handed in their firearms authorisation tickets.
Senior Met police commanders are in crisis discussions to try to ensure the Capital has an adequate armed response to firearms incidents.
The military has been put on standby to respond in the event of a terrorist attack.
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One armed policing source told GB News: "Virtually everyone on ARVs (Armed Response Vehicles) has asked for a period of reflection.
"There were two cars out last night instead of 15. It’ll be the same tonight… maybe."
The source said that firearms instructors were asked to act up and take on firearms patrol duties, but those instructors also said they were taking a period of reflection and handed in their tickets as well.
"No one now knows if they can instruct on courses without a blue card, so training may stop next week," the source said.
Mutual Armed Response Vehicle aid from other forces has also been requested.
Met Police plunged into crisis by firearms officers 'stepping back' en masse in protestPA
But GB News understands many armed officers from forces outside London have refused requests to cover in the Capital.
In another show of apparent solidarity with their Met police colleagues, many City of London Armed Response Vehicle officers have also decided to stand back from armed duties.
The source said the situation with Counter Terror Armed officers was exacerbated by a visit from one of the Met’s Deputy Assitant Commissioners.
Those elite firearms officers had said they would respond to threats to life and terrorism incidents.
The source claims the senior officer said, "it doesn’t work like that" and so every Counter Terrorism Firearms Officer on duty handed in their firearms authorisation tickets.
The crisis engulfing the Met follows a decision by the Crown Prosecution Service to charge a Met firearms officer with murder last week, over the shooting death of an unarmed black man last year.
Chris Kaba, had been driving a car linked to gun crime in Streatham Hill, south London on 5 September last year, when the vehicle was stopped by armed officers.
In the operation to detain Mr Kaba, a firearms officer discharged his weapon and the 24-year-old was shot in the head.
The Home Secretary has stepped into the row, offering her support to firearms officers and launching an urgent review into armed policing.
In a statement, Met Police said: "Senior officers, including the Commissioner, have been meeting with firearms officers in recent days as they reflect on the CPS decision to charge NX121 with murder.
"Many are worried about how the decision impacts on them, on their colleagues and on their families. They are concerned that it signals a shift in the way the decisions they take in the most challenging circumstances will be judged.
"A number of officers have taken the decision to step back from armed duties while they consider their position.
"We are in ongoing discussions with those officers to support them and to fully understand the genuinely held concerns that they have.
"The Met has a significant firearms capability and we continue to have armed officers deployed in communities across London as well as at other sites including Parliament, diplomatic premises, airports etc.
"To ensure that we can continue to keep the public safe and respond to any eventualities, since Saturday evening Met firearms officers have been supported by a limited number of armed officers from other UK forces.
"The Ministry of Defence has agreed to a request to provide the Met with counterterrorism support should it be needed.
"This is a contingency option that would only be used in specific circumstances and where an appropriate policing response was not available.
"Armed forces personnel will not be used in a routine policing capacity.
"We will keep these measures under review. Met officers still make up the vast majority of armed resources deployed across London."