Boris Johnson’s controversial comments about burka-wearing women gave the impression the Tories are “insensitive to Muslim communities”, according to an independent review into alleged discrimination in the party.

The inquiry found anti-Muslim sentiment was seen at local association and individual levels but claims of “institutional racism” were not borne out by evidence of the way complaints were handled.

Tory party chairwoman Amanda Milling apologised to “anyone who has been hurt by discriminatory behaviour of others or failed by our system”.

One of the issues highlighted by the report was the Prime Minister’s 2018 Daily Telegraph column in 2018 which described Muslim women who wear the burka as looking like “letterboxes” and “bank robbers”.

The review, led by Professor Swaran Singh, said the leadership of the Conservative Party “ought to set a good example for appropriate behaviours and language”.

The Prime Minister was cleared by a majority on an independent panel over a complaint he broke the party’s code of conduct in relation to the article.

Mr Johnson said he was “sorry for any offence taken” over his journalism and told Prof Singh’s investigation: “Would I use some of the offending language from my past writings today? Now that I am Prime Minister, I would not.”

The Singh Investigation said several interviewees who spoke to the inquiry considered Mr Johnson’s language “discriminatory and unacceptable”.

In response to Mr Johnson’s assertion he would not make such remarks now, the report said “using measured and appropriate language should not be a requirement solely for senior people, but ought to be expected throughout the Conservative Party”.

The investigation also examined the controversial and unsuccessful mayoral campaign Zac Goldsmith – now Lord Goldsmith of Richmond Park – ran in London against Sadiq Khan in 2016, during which he accused his Muslim Labour rival of associating with extremists.

The report said Lord Goldsmith “accepts poor judgement in the way his campaign was conducted but forcefully denies harbouring anti-Muslim sentiments or using such sentiments for political advantage”.

The report said high-profile cases like Mr Johnson’s and Lord Goldsmith’s “give the impression to many that the Party and its leadership are insensitive to Muslim communities”.

Prof Singh told PA: “I’m not saying that the party leadership is insensitive to Muslim communities. I’m saying that the perception is very strong.”

The inquiry carried out by Prof Singh, a former commissioner at the Equality and Human Rights Commission, was established by the party following a series of allegations about Islamophobic behaviour in the party and was widened to consider all forms of discrimination.

From 2015-2020 the party’s central database recorded 1,418 complaints relating to 727 incidents of alleged discrimination – an average of 237 complaints about 122 incidents a year in a party of 200,000 members.

More than two-thirds of the incidents – 496 cases – related to Islam and 74% of all the cases involved social media activity.

Around a third of cases – 231 – resulted in a sanction, with 50% resulting in a suspension and 29% in an expulsion from the party.

No action was taken in 418 incidents for reasons including the complaint being in relation to someone who was not a party member, insufficient evidence, or a prior investigation.

There was no evidence that complaints related to Islam are treated differently from those related to other forms of discrimination, nor did the panel find evidence of attempts to pressure or interfere with the handling of individual complaints.

But Prof Singh told PA the complaints process was “clunky, cumbersome and slow, and not transparent”.

The report acknowledged that “anti-Muslim sentiment remains a problem” within the Conservative Party.

But the investigation did not find evidence of a party which “systematically discriminated against any particular group”.

Ms Milling said the party accepted all the recommendations set out by the Singh report.

“We held this investigation to address these allegations to make sure that any instances of discrimination are isolated and to look at how we can improve and strengthen our complaints process,” she said.

“The Conservative Party will continue to take a zero-tolerance approach to discrimination of any kind and take immediate action to improve our handling of complaints.”

Former Tory chairwoman Baroness Warsi, who has accused the party of “institutional racism”, said the findings of the report vindicated her six-year long campaign and showed evidence of a system that “failed to protect victims of racism”.

But she criticised the “pre-determined public view” of Prof Singh for not accepting the charge of institutional racism.

Former chancellor Sajid Javid, who made the commitment to hold an inquiry into Islamophobia a key issue in the 2019 Tory leadership election, said the investigation found “distressing examples of anti-Muslim sentiment at local association and individual levels, as well as serious shortcomings in the party’s complaints process”.

The Muslim Council of Britain (MCB) said the Equalities and Human Rights Commission (EHRC) must determine whether the party broke the law.

MCB general secretary Zara Mohammed said: “The Singh Investigation report rightly acknowledges the scale of Islamophobia in the Conservative Party and provides some valuable recommendations.

“The investigation primarily deals with form over substance. Procedure is important, but it needs to be underpinned by dealing with the deep-seated issues of institutional racism.”

The report was described as a “whitewash” by Muslim Engagement and Development (Mend).

Mend chief executive Azhar Qayum said: “The report fails to address the pervasive climate of Islamophobia across the party which produces complaints in the first place, instead dismissing such issues as merely giving the ‘impression’ of Islamophobia – a conclusion that is little more than gaslighting.

“Mend has thus had no choice but to insist that the EHRC launch its own investigation.”

The EHRC said it will carefully evaluate Prof Singh’s findings and the Tory response.

Shadow women and equalities secretary Marsha de Cordova said: “This report is a damning indictment of the discrimination rife in the Conservative Party, and it goes all the way up to the Prime Minister.”

The report called on the Tories to introduce sweeping changes to the complaints process, publishing an action plan within six weeks to set out how it will respond, followed by a six-month progress report and a one-year review carried out by an appropriate body.

Within six weeks, the party should review its social media rules and within six months develop training on “acceptable” behaviour online.

Within a year, the report said the party should produce and implement a single, mandatory code of conduct across the entire membership in England, Wales and Northern Ireland.