Scotland Yard has been forced to admit it was “unacceptable” for one of its official Twitter accounts to apparently criticise the mayor of London, Sadiq Khan, leading him to accuse the force of amplifying misleading information. Khan tackled the suggestion – made in a now-deleted tweet by the verified “Met Police Taskforce” – that he did not understand the rules for disciplining officers. It came as the London mayor said he would not support the choice of the home secretary, Priti Patel, to replace the Met commissioner, Cressida Dick, unless whoever was chosen understood “the importance of addressing these deep cultural issues” within the force, such as racism, sexism and bullying. The shock announcement of Dick’s departure has caused turmoil in the Met and for political leaders, including Khan, in whom the Police Federation has declared its members have “no confidence”. Tensions escalated further on Thursday when the Times reported that Dick had told colleagues that Khan had given her an ultimatum to sack senior officers in Charing Cross police station or face suspension herself. Khan insisted during a phone-in on LBC: “It is not the case the commissioner was given an ultimatum to sack them or be sacked.” However, he said he was “angered and disgusted” by the views of some officers at Charing Cross station and “concerned about the impact on trust and confidence” after it was revealed they exchanged WhatsApp messages about hitting and raping women, as well as the deaths of black babies and the Holocaust. Khan criticised a tweet by an official Met account which retweeted a post pointing out that the process for sacking officers is independent of chief constables, with the comment: “Exactly this.” Several hours after the post was deleted, a spokesperson for the Met said the tweet was “unacceptable and shouldn’t have been shared” from an official account. They said senior officers were “addressing the matter” and would remind colleagues “they are expected to be independent and impartial at all times, on and off duty, including on social media”. The mayor suggested the intervention was unhelpful, referring to a recommendation by the Independent Office for Police Conduct that found widespread evidence of bullying and discrimination among officers. Khan said: “When you have Met police accounts amplifying information that is misleading, how is it possible for officers concerned about behaviour of other officers to come forward? “Why are we surprised when whistleblowers don’t come forward if this is the attitude both the IOPC talked about and you’ve exemplified in relation to a blue-ticked account?” With the search for Dick’s replacement now under way, Khan said he believed Patel would be “incredibly professional” in the recruitment process. However, he said that while he hoped to be consulted, he would not support Dick’s successor if “I don’t have confidence that he or she understands the importance of addressing these deep cultural issues”. Khan also resisted any suggestion he should lean on police to encourage the Met to publish photos of Downing Street parties, which the Guardian revealed earlier this week the government expected Scotland Yard would not release. “Just think how inappropriate it would be for me, a Labour mayor, getting involved in operational matters where a Conservative politician is being investigated,” he said. “There are some countries around the world where the police do have their arms twisted in relation to operational issues. I think it is right in our system where I have got no influence in relation to whether the police do investigate Boris Johnson, what is published and so forth. “I have always, as the mayor, been cognisant of the importance of me understanding which side of the line I should be on.”