Sadiq Khan’s spat with Donald Trump shows no sign of resolution, as the Mayor of London branded him a “6ft 3 child in the White House”.

It is the latest insult to be fired between Khan and the US president, in what has been a long-running feud.

Trump called Khan a “stone cold loser”, mocked his height and misspelt his name in a tweet sent as he touched down in Air Force One for a state visit to the UK earlier this month.

And more recently the president dubbed Khan a “disaster” on Twitter and called him a “national disgrace who is destroying the city of London”, as he criticised the mayor’s record on crime in the capital.

In a room full of teachers at the Together For Education event in Westminster’s Central Hall on Saturday Khan joked that he had made sure to switch his phone off.

He added: “For those of you that have your phones on, if somebody starts tweeting about me – a 6ft 3 child in the White House – can you let me know?”

The remark prompted laughter, cheers and applause from those gathered.

It was the latest salvo in a transatlantic exchange that has seen Khan describe Trump as a “poster boy for racists” and remark that the president appears “obsessed” with him.

Earlier this week Tory leadership hopeful Jeremy Hunt said he agrees “150%” with Trump’s assessment of Khan’s record on tackling knife crime.

Foreign Secretary Hunt said the president “has his own style” and he “would not use those words myself”.

He added: “But the sentiment is enormous disappointment that we have a Mayor of London who has completely failed to tackle knife crime and has spent more time on politics than the actual business of making Londoners safer and in that I 150% agree with the president.”