US President Donald Trump has once again criticized the Mayor of London Sadiq Khan calls him a "national shame" that destroys Britain's capital.
His comments came after five attacks in London in less than 24 hours left three men dead and three others injured.
Supervisor Jeremy Corbyn said it was "absolutely horrible" Mr Trump used the "tragedy of people who were murdered to attack the mayor".
President Trump's tweets follow a prolonged feud between the two men.
Retweeting a post by right commentator Katie Hopkins about the weekend's violence in London, the president said Khan was "a disaster" and the capital needed a new mayor.
Mr Trump later followed it up with another post and said, "He is a national shame that is the battles in the city of London!" victims' families and he "will not waste his time reacting to this type of tweet".
The mayor focused on supporting the city's communities and the "overstretched" emergency services, he added.
Corbyn tweeted to defend Khan and said he "rightly supported the police to do their job while Katie Hopkins spread hateful and fragmented rhetoric."
Police have made 14 arrests – including several boys and a girl – after the five separate attacks.
An 18-year-old man was pushed to death on Friday afternoon in Wandsworth, southern London, when a few minutes later a 19-year-old man was killed in Plumstead in southeast London.
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A man in the 30s died after he was stabbed in Tower Hamlets on Saturday afternoon.
In the early hours of Saturday, two men were pushed into Clapham and another was stabbed in Brixton.
Death takes the total number of murders in London in 2019 to 56. This time last year, there were 77 murders, of which 48 were stabbings.
President Trump and Khan have collapsed many times before.
The president called Khan a "stone loser who should focus on crime in London" just before landing in Stansted before his three-day state visit to the UK earlier this month.
It followed comments from the Mayor of London that Britain would not "roll out the red carpet" for Mr Trump during his visit.
Previously, Trump has challenged Khan to an IQ test and has been critical of his response to the London Bridge attack in 2017.