Jeremy Corbyn leapt to Sadiq Khan's defence today after Donald Trump stepped up his Twitter war with the London mayor.
The US President called Mr Khan a "disaster", retweeting a post by right-wing commentator Katie Hopkins, which branded the UK capital "Londonistan" - a reference to the mayor's Muslim religion and Pakistani heritage.
It followed the latest violence in London, where three men were killed in separate attacks in less than 24 hours.
Two teenagers were murdered within minutes of each other in different parts of the capital on Friday, while a man was stabbed to death on Saturday afternoon.
Retweeting Hopkins' post, the President said the capital needed a new mayor "ASAP".
Mr Trump tweeted: "LONDON needs a new mayor ASAP. Khan is a disaster - will only get worse!"
The original post by Hopkins called the capital "Stab-City" and "Khan's Londonistan" alongside two screenshots of BBC News articles detailing the violence.
The Labour leader hit back: " Sadiq Khan is rightly supporting the police to do their job while Katie Hopkins spreads hateful and divisive rhetoric.
"They seek to divide at a time we need to come together."
A spokesman for the mayor said: "Sadiq is focusing on supporting London's communities and over-stretched emergency services.”
Labour MP Anna Turley tweeted: “‘Londonistan’. Get in the bin you pair of massive racists.”
She added: "Really shouldn’t have to explain how the tweet is racist. ‘Londonistan’ - a blatant attempt to link immigration and crime rates."
