Dame Cressida Dick said the number of Tasers in use in the capital had risen by 50 per cent over the last two years to 6,500.
Another increase was expected later this month but it was not “practicable or necessary” to follow other forces by giving stun guns to every officer, she told LBC radio.
“We're taking part in the National Police Chiefs' Council review of all aspects of officer safety and indeed my own board is meeting in two weeks' time, so I anticipate that we will be announcing a further uplift after that,” Dame Cressida said. “About 20 per cent of my people have said in a survey they don’t really want to carry Taser, thank you very much. It is a very powerful bit of kit, it’s also potentially very dangerous.
“You’ve got to be a really good decision-maker, you’ve got to be really fit.”
The Police Federation of England and Wales, which represents rank-and-file officers, has been leading calls for Tasers to be given to all officers following incidents including a machete attack on a police officer in London and the death of PC Andrew Harper, who was dragged under a vehicle last month, weeks after he got married.
Chair John Apter wrote to the home secretary last month calling for the government to provide new funding for more officers to be trained and equipped with Tasers, but the request was not granted in Sajid Javid’s spending review.
“Officers feel vulnerable when they’re out on patrol and they know that if something happens their nearest backup is 20 or 30 minutes away,” Mr Apter told The Independent. “Tasers are lifesavers, it shouldn’t take a tragedy to have this debate.”
Amnesty International UK said the weapons had been linked to hundreds of deaths in the US and urged caution over expanding their use in Britain.
Allan Hogarth, the charity’s head of policy, said: “Police officers do a difficult job, and we're not against them receiving Tasers as long as they're only being deployed by highly trained specialist officers in situations where they're trying to prevent loss of life or serious injury.”
The chief constables of Durham and Northamptonshire police have recently announced that all frontline officers would be offered the weapons.
Support for Tasers among police chiefs varies, with some fearing that their increased use damages public relations and undermines the unarmed nature of British policing.
Police record mental health as a factor in 14 per cent of Taser incidents, which rose by 50 per cent in 2017-18.
The vast majority of the 17,000 times where Tasers were drawn or used resulted in arrests, but 950 people were admitted to hospital and 750 were detained under the Mental Health Act.
Tasers were not fired in 85 per cent of incidents, where the most common reasons cited by officers were the protection of themselves and colleagues.
Dame Cressida called Tasers a “great bit of kit that has saved lives” and said the Metropolitan Police had been increasing the number of stun guns and the number of officers trained and permitted to use them.
But she said officer safety was “not all about Taser”, detailing plans to supply longer batons, incapacitant spray and spit hoods.
The debate follows Boris Johnson's vow to recruit 20,000 more officers and boost stop and search powers, following years of government cuts to policing.
The Metropolitan Police commissioner said her force was also aiming to gain 6,000 extra officers, arguing the amount was “proportionate given the challenges we face with violence, the scale of the city, the changing demographics, the demands which have gone up, the protests that we are dealing with”.
The government has been criticised for announcing the 20,000 policy before planning its implementation, with the head of the National Police Chiefs’ Council revealing that up to half a million people may have to apply to reach the target.
Mr Johnson was also accused of using police as a “political tool” after making a speech about Brexit standing in front of student police officers earlier this month.
Join our commenting forum
Join thought-provoking conversations, follow other Independent readers and see their replies