The mayor of London, Sadiq Khan, has attacked Boris Johnson for his past use of “homophobic language” and called on the Conservative leadership candidate to recognise that “language matters” as thousands celebrated Pride in the capital.

The Tory frontrunner has been criticised for historic remarks on homosexuality, including calling gay men “tank-topped bumboys” in a 1998 column in The Daily Telegraph.

“You’ve got the next prime minister using homophobic language,” said Mr Khan as he launched the Pride in London parade on Saturday.

“When you speak to members of the LGBT+ community, they will tell you that some of the homophobia they suffered, the attackers used this language, the same sort of language he’s used.

“What I want to see from our prime minister, if it is Boris Johnson, it looks like it will be, is him realising that language matters.”

London Pride 2019: The Best Rainbow Outfits Show all 25 1 /25 London Pride 2019: The Best Rainbow Outfits London Pride 2019: The Best Rainbow Outfits SOCIAL-Pride-13575800.jpg A reveller wears a hat made of plastic dolls during the Pride in London Parade in central London. PRESS ASSOCIATION Photo. Picture date: Saturday July 6, 2019. See PA story SOCIAL Pride. Photo credit should read: Dominic Lipinski/PA Wire Dominic Lipinski PA London Pride 2019: The Best Rainbow Outfits 1160390756.jpg LONDON, ENGLAND - JULY 06: A parade goer during Pride in London 2019 on July 06, 2019 in London, England. (Photo by Tristan Fewings/Getty Images for Pride in London) Tristan Fewings Getty Images for Pride in London London Pride 2019: The Best Rainbow Outfits AFP-1IE266.jpg A member of the Lesbian, Gay, Bisexual and Transgender (LGBT) community poses for a photograph at the annual Pride Parade in London on July 6, 2019. (Photo by Niklas HALLE'N / AFP)NIKLAS HALLE'N/AFP/Getty Images NIKLAS HALLE'N AFP/Getty Images London Pride 2019: The Best Rainbow Outfits 1160388766.jpg LONDON, ENGLAND - JULY 06: A parade goer during Pride in London 2019 on July 06, 2019 in London, England. (Photo by Tristan Fewings/Getty Images for Pride in London) Tristan Fewings Getty Images for Pride in London London Pride 2019: The Best Rainbow Outfits AFP-1IE25J.jpg A member of the Lesbian, Gay, Bisexual and Transgender (LGBT) community poses for a photograph at the annual Pride Parade in London on July 6, 2019. (Photo by Niklas HALLE'N / AFP)NIKLAS HALLE'N/AFP/Getty Images NIKLAS HALLE'N AFP/Getty Images London Pride 2019: The Best Rainbow Outfits AFP-1IE262.jpg A member of the Lesbian, Gay, Bisexual and Transgender (LGBT) community poses for a photograph at the annual Pride Parade in London on July 6, 2019. (Photo by Niklas HALLE'N / AFP)NIKLAS HALLE'N/AFP/Getty Images NIKLAS HALLE'N AFP/Getty Images London Pride 2019: The Best Rainbow Outfits SOCIAL-Pride-15064325.jpg Dancers take part in the Pride in London Parade in central London. PRESS ASSOCIATION Photo. Picture date: Saturday July 6, 2019. See PA story SOCIAL Pride. Photo credit should read: Dominic Lipinski/PA Wire Dominic Lipinski PA London Pride 2019: The Best Rainbow Outfits SOCIAL-Pride-11404395.jpg A reveller ahead of the Pride in London Parade in central London. PRESS ASSOCIATION Photo. Picture date: Saturday July 6, 2019. See PA story SOCIAL Pride. Photo credit should read: Dominic Lipinski/PA Wire Dominic Lipinski PA London Pride 2019: The Best Rainbow Outfits 2019-07-06T135655Z-518085815-RC1DC9E56ED0-RTRMADP-3-GAY-PRIDE-BRITAIN.JPG A participant takes part in the annual Pride in London parade, in London, Britain July 6, 2019. REUTERS/Henry Nicholls HENRY NICHOLLS REUTERS London Pride 2019: The Best Rainbow Outfits 1160394874.jpg LONDON, ENGLAND - JULY 06: A parade goer during Pride in London 2019 on July 06, 2019 in London, England. (Photo by Tristan Fewings/Getty Images for Pride in London) Tristan Fewings Getty Images for Pride in London London Pride 2019: The Best Rainbow Outfits AFP-1IE25F.jpg A member of the Lesbian, Gay, Bisexual and Transgender (LGBT) community poses for a photograph at the annual Pride Parade in London on July 6, 2019. (Photo by Niklas HALLE'N / AFP)NIKLAS HALLE'N/AFP/Getty Images NIKLAS HALLE'N AFP/Getty Images London Pride 2019: The Best Rainbow Outfits 1160394805.jpg LONDON, ENGLAND - JULY 06: A parade goer during Pride in London 2019 on July 06, 2019 in London, England. (Photo by Tristan Fewings/Getty Images for Pride in London) Tristan Fewings Getty Images for Pride in London London Pride 2019: The Best Rainbow Outfits 1160389308.jpg LONDON, ENGLAND - JULY 06: Parade goers during Pride in London 2019 on July 06, 2019 in London, England. (Photo by Tristan Fewings/Getty Images for Pride in London) Tristan Fewings Getty Images for Pride in London London Pride 2019: The Best Rainbow Outfits 2019-07-06T141501Z-1727001309-RC15E254D610-RTRMADP-3-GAY-PRIDE-BRITAIN.JPG Participants take part in the annual Pride in London parade, in London, Britain July 6, 2019. REUTERS/Henry Nicholls HENRY NICHOLLS REUTERS London Pride 2019: The Best Rainbow Outfits 1160386919.jpg LONDON, ENGLAND - JULY 06: Parade goers during Pride in London 2019 on July 06, 2019 in London, England. (Photo by Tristan Fewings/Getty Images for Pride in London) Tristan Fewings Getty Images for Pride in London London Pride 2019: The Best Rainbow Outfits 1160391640.jpg LONDON, ENGLAND - JULY 06: A parade goer during Pride in London 2019 on July 06, 2019 in London, England. (Photo by Tristan Fewings/Getty Images for Pride in London) Tristan Fewings Getty Images for Pride in London London Pride 2019: The Best Rainbow Outfits AFP-1IE24L.jpg Members of the Lesbian, Gay, Bisexual and Transgender (LGBT) community pose for a photograph before taking part in the annual Pride Parade in London on July 6, 2019. (Photo by Niklas HALLE'N / AFP)NIKLAS HALLE'N/AFP/Getty Images NIKLAS HALLE'N AFP/Getty Images London Pride 2019: The Best Rainbow Outfits wenn36683721.jpg Pride Parade London 2019. Over 500 LGBT+ parade groups march through central London to celebrate the diversity of the LGBT+ community. Featuring: Atmosphere, View Where: London, United Kingdom When: 06 Jul 2019 Credit: Wheatley/WENN MAAA/ZDS Wheatley/WENN London Pride 2019: The Best Rainbow Outfits 1160392129.jpg LONDON, ENGLAND - JULY 06: A parade goer during Pride in London 2019 on July 06, 2019 in London, England. (Photo by Tristan Fewings/Getty Images for Pride in London) Tristan Fewings Getty Images for Pride in London London Pride 2019: The Best Rainbow Outfits GettyImages-1160388695.jpg LONDON, ENGLAND - JULY 06: Parade goers during Pride in London 2019 on July 06, 2019 in London, England. (Photo by Tristan Fewings/Getty Images for Pride in London) Tristan Fewings Getty Images for Pride in London London Pride 2019: The Best Rainbow Outfits 1160390632.jpg LONDON, ENGLAND - JULY 06: A parade goer during Pride in London 2019 on July 06, 2019 in London, England. (Photo by Tristan Fewings/Getty Images for Pride in London) Tristan Fewings Getty Images for Pride in London London Pride 2019: The Best Rainbow Outfits 1160390647.jpg LONDON, ENGLAND - JULY 06: A parade goer during Pride in London 2019 on July 06, 2019 in London, England. (Photo by Tristan Fewings/Getty Images for Pride in London) Tristan Fewings Getty Images for Pride in London London Pride 2019: The Best Rainbow Outfits SOCIAL-Pride-12534864.jpg A reveller during the Pride in London Parade in central London. PRESS ASSOCIATION Photo. Picture date: Saturday July 6, 2019. See PA story SOCIAL Pride. Photo credit should read: Dominic Lipinski/PA Wire Dominic Lipinski PA London Pride 2019: The Best Rainbow Outfits 1154024961.jpg LONDON, ENGLAND - JULY 06: Amanda Lepore attends a pride brunch hosted by House of Holland and The London EDITION in aid of Albert Kennedy Trust at Berners Tavern on July 6, 2019 in London, England. (Photo by David M. Benett/Dave Benett/Getty Images for The London EDITION) David M. Benett Dave Benett/Getty Images for The London Pride 2019: The Best Rainbow Outfits 1154024912.jpg LONDON, ENGLAND - JULY 06: Maxim Magnus attends a pride brunch hosted by House of Holland and The London EDITION in aid of Albert Kennedy Trust at Berners Tavern on July 6, 2019 in London, England. (Photo by David M. Benett/Dave Benett/Getty Images for The London EDITION) David M. Benett Dave Benett/Getty Images for The

Mr Johnson also previously criticised the Labour Party’s “appalling agenda, encouraging the teaching of homosexuality in schools, and all the rest of it” in a column for The Spectator in 2000.

The favourite to become the next prime minister issued a tweet of support for Pride earlier today, saying “Britain leads the world in LGBT+ equality”. He also reminded his followers of the time he once wore a pink Stetson.

“Salute all those celebrating #PrideInLondon today,” Mr Johnson tweeted. “I have fond memories of my pink Stetson march as Mayor!

Sadiq Khan at Saturday’s parade (Getty Images for Pride in London)

“Britain leads the world in LGBT+ equality and I’ll continue to champion the cause if I am lucky enough to become our country’s prime minister.”

The former foreign secretary has been dogged by questions about his long history of offensive remarks, particularly his 2018 Telegraph column comparing veiled Muslim women to “letter boxes”.

At a hustings in Nottingham on Saturday, Mr Johnson asked by a Tory member if he would be “a fitting prime minister for everyone, including minority groups” after his “derogatory and arguably racist comments in the past, for example about women wearing the burka”.

Mr Johnson claimed the column was “a strong, liberal defence of the right of women to wear the burka”. He also pointed out that he had been mayor of London, saying the city was “the most diverse on earth”.

This year’s Pride events come 50 years since the Stonewall uprising in New York – a moment which changed recognition of gay rights around the world.