Soldiers will be drafted in to replace armed police officers following a mass walkout by firearms teams to protest against the decision to charge one of their colleagues with murder.

More than 300 officers – 10 per cent of all firearms staff – have refused to carry a gun, forcing Scotland Yard to submit a formal request to the Ministry of Defence (MoD) for help with counter-terror policing.

On Sunday Sir Mark Rowley, the Metropolitan Police commissioner, issued an open letter calling for an overhaul of the way police officers are treated by the justice system and better legal protection for those who use force while on duty.

His comments came just hours after Suella Braverman, the Home Secretary, gave her backing to firearms officers and said she would launch a review “to ensure they have the confidence to do their jobs while protecting us all”.

The Telegraph understands that special forces could be asked to step in to cover for Counter Terrorism Specialist Firearms Officers, who are among those currently refusing to carry guns.

The unit is on duty round the clock to provide a response should there be a major terrorist incident.

The walkout came after an officer, identified as NX121, appeared in court accused of murdering Chris Kaba, 23, an unarmed black man who was shot dead during a police operation in south London last September.