London Mayor Sadiq Khan has fired another linguistic shot at President Donald Trump, calling him “a six-foot-three child.”

According to The Guardian, Khan made the blistering remark at an education conference in Westminster’s Central Hall on Saturday just after assuring the crowd he had switched off his phone.

“For those of you that have your phones on, if somebody starts tweeting about me ― a six-foot-three child in the White House ― can you let me know?” he joked.

The war of words began earlier this month when the mayor penned an op-edin The Observer, describing Trump’s rhetoric as a throwback to “fascists of the 20th century” and condemning him for “lying deliberately and repeatedly to the public.”

Taking his argument further, Khan said it would be “so un-British” to offer Trump a red-carpet rollout for his U.K. summit, which was only two days away

The op-ed sent the president into a tweet-filled rage.

In retaliation, Trump lashed out at Khan, whom he deemed a “terrible” mayor and “stone cold loser.” His decision to be “foolishly ‘nasty’” to the leader of his “most important ally” was a mistake, the president warned.