The Metropolitan police have said they would press ahead with plans to allow armed officers to patrol areas with their guns visible and ready to use, in an effort to quell knife crime and violent gangs.

News of the plans provoked criticism and, the Guardian has learned, has sparked a rift with Sadiq Khan, who was not consulted despite the force being accountable in law to the London mayor.

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The plans represent a change to traditional policing, where firearms officers are only deployed when there was a fear suspects may have weapons.

The Met leadership – from the commissioner, Cressida Dick, downwards – stressed the plan would not amount to routine armed patrols in the capital.

Some parts of central London have armed patrols to counter the threat of terrorist attack, but the new plans being developed by the Met would send armed foot patrols to residential areas with high violent crime.

Commander Kyle Gordon, the head of firearms for the Met, said the force would consult further before a decision was made to approve or drop the plan by the leadership of Britain’s biggest police force.

Gordon said he had helped to formulate the plan. He said that so far the reaction from people the Met had consulted was largely positive, adding: “Would there be benefit in the [armed] officer getting outside their vehicles, and either being static or walking short distances in an area to do two things; be seen in instances where we believed that would enhance community confidence and where we believe it would disrupt and deter any violent activity?”

Gordon said that officers on armed foot patrols would carry their main weapon and wear a pistol on their hip. “If they leave the vehicle to do a patrol their weapons would be accessible and visible.”

He added: “What we are asking is can we use all the assets [of the Met], including armed officers, to enhance confidence and deter activity.”

Gordon said the presence of officers could deter crimes such as burglaries, and armed officers on foot patrol could do so with gang and knife crime.

He said officers would not open fire if a suspect with a knife refused to comply. “If the current standard is met, where officers have an honestly held belief where someone’s life is in danger, an officer has a right to use force.”

He said armed officers were trained to a higher standard to “deal with conflict” and also carry Tasers.

The mayor’s office has not publicly criticised the plan but one senior source said the view was that the Met had made a mess of how it had handled the plans so far, and had blundered in not consulting the mayor, but there was still full confidence in the commissioner.

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Details had leaked out in an email sent to some community figures to seek their views. Len Duvall, a Labour member of the London assembly, said : “I welcome the rowing back …… Any new tactics needs to be effective and appropriate.”

Victor Olisa, a former commander of Tottenham in north London, which has been an area with above average levels of violent crime and gang activity, said: “With proper consultation I think it is a good idea. When I was in charge of Tottenham, I believed the people deserved the same protection as other parts of London. In Westminster the risk was terrorism; in Tottenham serious violence was the bigger risk.

“The assumption would be these officers would be in areas of large black population. Police need to make sure it is not misinterpreted.”