(CNN) A spate of violence in London sparked another vitriolic tweet from Donald Trump blaming mayor Sadiq Khan for the city's knife crime problem -- but is the British capital as dangerous as the US President suggested?

Four people were murdered across London over the weekend, according to the city's Metropolitan Police.

On Saturday, Trump criticized Sadiq Khan for failing to curb violence while retweeting a post by right-wing commentator Katie Hopkins who denounced London as "Stab-City." The messages were the latest escalation in a long-running war of words between the US President and Khan.

But going beyond the rhetoric to look at US and UK crime statistics, London appears to have far less of a problem with violent crime than many major US cities.

Last year, there were 136 homicides in the UK capital, according to Metropolitan Police figures . That translates to a rate of 1.54 homicides per 100,000 people.