The number of Islamophobic posts aimed at Sadiq Khan has more than doubled in a year, according to fresh analysis that suggests the London mayor remains a lightning rod for racist abuse.

Almost 28,000 social media posts referring to Khan included a key Islamophobic phrase last year, a huge increase on the 12,000 sent a year earlier and a more than eight-fold increase from 2022, according to the analysis commissioned by the Greater London authority (GLA).

This year, Khan has already been mentioned alongside Islamophobic keywords 2,180 times. The vast majority of abuse was posted on X, with a record number of posts referring to Khan posted from the UK in the past year. The research found that 89% of the offending Islamophobic posts about Khan since 2015 had originated on the platform.

Khan has been one of the most prominent voices speaking about online abuse, warning that the west must now face up to a “century-defining challenge” after a resurgence of the far right. He has criticised X’s owner, Elon Musk, whom he blames for making the problem of online abuse far worse. Under Musk, the accounts of far-right figures such as Tommy Robinson have been reinstated.

Khan has also called for stricter laws on harmful content, saying the UK’s new Online Safety Act should be “the floor, not the ceiling” of action taken to tackle online abuse. The act deals only with content deemed illegal.

The peak in Islamophobic abuse aimed at Khan came in 2019, with just under 42,000 messages. However, this was heavily skewed by posts coming from India, after protests at the Indian high commission in London and misinformation related to Kashmir.

Patrik Hermansson, senior researcher at Hope Not Hate, said that Khan’s Muslim identity “makes him a target that people project their Islamophobic conspiracy theories on”. He added: “There is a wider anti-migrant and Islamophobic narrative and conspiracy theory that London is becoming a Muslim majority city and that this is intentionally accelerated by Khan.”

Previous research showed that Khan has received hundreds of thousands of openly racist and / or racially oriented abusive messages on social media since he was elected London mayor in 2016. He has long been a target of posts from Donald Trump. In 2017, Trump described the London mayor as a “national disgrace” who was destroying the city.

In 2018, Trump appeared to blame the mayor for a rise in immigration and associated it with crime, saying in an interview: “I think he has done a bad job on crime, if you look, all of the horrible things going on there, with all of the crime that is being brought in.”

At the time, David Lammy, who is now the foreign secretary, accused the US president of being a “racist” who “hates that London chose a Muslim mayor”. Since taking office, Lammy has dismissed his past criticism of Trump and described him as “someone that we can build a relationship with in our national interest”.

It comes as a prominent Reform donor said he had been threatened with the removal of his OBE over comments he made about Khan. Charlie Mullins, the founder of Pimlico Plumbers who has also previously funded the Conservatives, was heavily criticised by the honours forfeiture committee for “bringing the honours system into disrepute”.

The 72-year-old was suspended from X in 2023 after saying “someone should kill” Khan, as part of a discussion about London’s ultra-low emission zone scheme (Ulez). He also replied to a user who called on him to run against Khan by saying: “I am on it, and it’s time to dump the Muslim mayor.” He later apologised unreservedly for the remarks.

Mullins argued the threat over his honour was a politically motivated move, accusing Starmer of involvement. A government source said the claims were “completely unfounded and inaccurate”. They said the committee was “entirely apolitical” and that no ministers or political appointees were involved in its decisions.

After a pledge from his lawyers that he would undertake “gender sensitivity and diversity training”, Mullins was last week told no action would be taken. However, he was warned that a further investigation could be launched “should any future behaviour make that necessary”.