Sadiq Khan London mayor election 2016
Sadiq Khan is Labour's candidate for London mayor at the May 2016 electionGetty

Sadiq Khan, Labour's London mayoral candidate, has suspended one of his close aides for posting offensive messages on Twitter. The former Shadow Minister's assistant, Shueb Salar, had allegedly posted "sexist and homophobic" tweets before he was hired by Khan in November 2014.

Confirming the suspension, a spokeswoman for the mayoral candidate said: "...clearly (these tweets) are serious issues". She added: "Shueb Salar has been suspended from Sadiq Khan's parliamentary office pending an investigation."

Salar had allegedly responded to the hashtag #HowToTreatALady on Twitter with: "Buy her a nice iron and extend the kitchen for her." Another June 2012 post read: "f**k all you hoes".

In another tweet he commented, "B***h please, don't be proud if every guy wants you. Cheap items have many buyers." Later, he had tweeted about the "funniest tube journey ever" – when "rowdy chavs were cussing these 2 gay guys for kissing". In a comment Salar had said: "Maybe they deserved it."

Another message posted in May 2012 read: "currently hating on all you faggots who have finished uni".

Even as Salar started working for Khan two years after the offensive messages had been posted on social media, Cabinet Minister Chris Grayling questioned Khan's judgment in employing him.

Grayling said: "These comments have absolutely no place in modern society. They raise serious questions about the judgment of Sadiq Khan who chose to employ this man despite his views being public, on a Twitter account followed by Khan himself.

"The mayor of London makes a large number of decisions about who to hire and how to spend public funds: his record shows Sadiq Khan can't make those decisions in a way that stands up for Londoners."

Khan is the bookies' favourite to succeed Boris Johnson in the mayoral elections scheduled for 5 May.