Dame Cressida Dick suggested random spot checks of officers’ phones and social media accounts, it was reported on Thursday.
The Metropolitan Police Commissioner also called for an “urgent” review of misconduct procedures after a misogyny and racism scandal at Charing Cross police station was exposed.
London Mayor Sadiq Khan had put Dame Cressida “on notice” following a watchdog report into “disgraceful” misconduct by officers at the West End station.
He demanded she implement a plan to clean up the Met and restore public confidence after racist, homophobic and misogynistic WhatsApp messages between officers were exposed.
According to the Times, Dame Cressida sent a letter on February 4 outlining how she would meet the mayor’s demands.
She resigned a week later, having lost the support of the mayor.
In the letter, the commissioner reportedly told Mr Khan that she had never said that culture issues were “just a few bad apples”.
“The problem is much wider than that, clearly, and it is my job to accelerate our work to root out unprofessional individuals and rotten teams, and raise standards across the board,” she reportedly wrote.
She is also said to have proposed an urgent discussion with Mr Khan and the government about whether police forces should be allowed to review the phone and social media accounts of officers and staff “on a random or with cause basis”.
“I do not underestimate the challenge of achieving change here within a national system, but a wide debate is needed and one I think we can lead from London,” she is said to have written.
Dame Cressida set out internal initiatives including a “hard-hitting” campaign against racism, harassment and discrimination, and announced a 100-strong team to provide oversight of standards
The Times reported earlier on Thursday that Dame Cressida told senior colleagues that Mr Khan threatened to suspend her after she resisted his demands to sack officers in the Charing Cross scandal.
Responding to the report, the mayor denied issuing Dame Cressida with an ultimatum.
Mr Khan said: “It is not the case that the commissioner was given an ultimatum to sack them or she would be sacked.”
The Met Police has been approached for comment.