Sadiq Khan’s speech on gender equality was halted by hecklers who stormed a conference and called for the London Mayor to be arrested.
The Mayor was speaking at the Fabian Society – a left-wing thinktank – about the modern-day threat to gender equality.
Shortly after he began his address he was interrupted by men, one of whom was holding up an American flag, who were calling for a citizen’s arrest of Mr Khan.
The demonstrators, from a group called the White Pendragons, were escorted from the venue by police.
Their outburst is believed to be in response to comments made by the Mayor about President Trump.
Mr Khan calmly sat down and flicked through a newspaper as the disruption was handled.
Video shared on social media appeared to show the moment the activists interrupted the speech, moments after the mayor was introduced to the stage.
One man could be heard addressing the audience with: “Ladies and gentlemen, we’re here today to make a non-violent, peaceful citizen’s arrest.”
Audience members started to heckle and slow-clap, during which security appeared.
However their attempts to eject those responsible for the disruption were initially met with aversion from the protesters, one of whom could be heard saying: “We stand under Common Law jurisdiction.
“If you touch us, you’ll be done for common assault. Please stand back, do not touch us. We’re not leaving, we’ve paid for a ticket.”
He then accused the Fabian Society of “subverting” the constitution.
When he resumed his speech Mr Khan tried to make light of the incident with a reference to Prime Minister Theresa May’s Tory conference speech which was interrupted by a prankster, saying: “On the plus side I wasn’t served with a P45.”
And in a dig at the US president after Mr Trump described himself as a “very stable genius”, Mr Khan said: “It is a pleasure to be here even though we were distracted by the actions of what some would call very stable geniuses.”
The protest is thought to be in response to Mr Khan saying US President Trump had “got the message” from Londoners after he cancelled his planned visit to the capital next month.
The US President was due to make the trip to London for the opening of the new £750 million US embassy in February.
But he has pulled out of the visit after threats of mass protests across the UK, with Mr Khan among those who had warned Mr Trump he would not be welcomed by Londoners.
After the President confirmed he had scrapped his planned trip, Mr Khan said such a visit would “without doubt” have been met by mass protests.
“It appears that President Trump got the message from the many Londoners who love and admire America and Americans but find his policies and actions the polar opposite of our city’s values of inclusion, diversity and tolerance,” the Mayor told the Standard.
“His visit next month would without doubt have been met by mass peaceful protests. This just reinforces what a mistake it was for Theresa May to rush and extend an invitation of a state visit in the first place.
“Let’s hope that Donald Trump also revisits the pursuit of his divisive agenda.”
In the speech the Mayor warned that gender equality could be at risk of stalling or even regressing.
“Not only is progress on gender equality plateauing, depressingly – we’re now faced with – for the first time in my lifetime – the threat of things going backwards,” he said.
“A new trend of pejoratively calling people ‘snowflakes’ or ‘social justice warriors’ – is being used as a weapon to shut down debate. We’ve seen the impact of this in the US and we cannot allow this narrative to take hold in Britain. We all have a responsibility as progressives to continue the fight for gender equality.”
He also spoke out about the responsibility men have to be “better allies so that when women speak out about sexual harassment – men listen, believe and act”.
“We all have a duty to create an environment where women feel empowered to speak out and to expose the injustice,” he added.