Johnson accuses London mayor of 'abject failure' to tackle knife crime
Boris Johnson has said Sadiq Khan needs to take responsibility for knife crime in London.
He described it as a "scandal" that the murder rate in the city was higher than in New York earlier this year.
The former foreign secretary accused the Mayor of London of blaming "everyone but himself" for the rising levels of attacks in the capital - while a spokesman for Mr Khan dismissed the comments as "desperate nonsense".
Writing in The Daily Telegraph, Mr Johnson said: "It is tragic that so many young lives are again being lost on the pavements of our capital.
"But for my money there is a further outrage - and that is the abject failure of the Mayor of London either to grip the problem, or even to take responsibility."
He added: "He (Mr Khan) blames everyone but himself, when it is his paramount duty to keep Londoners safe."
Mr Johnson said stop and searches "make a difference" and admitted that it was a "serious mistake" for the Home Office to move away from them in 2015.
He urged Mr Khan not to "berate" the police, but to "get behind" Scotland Yard.
The number of homicides in England and Wales increased from 533 in 2013/14 to 701 in 2017/18, while for the Metropolitan Police in London it went from 100 in 2013/14 to 153 in 2017/18.
The Met has weathered budget cuts of £600 million since 2011, and is now having to save hundreds of millions more.
Mr Khan has granted an extra £110 million to the force.
Commissioner Cressida Dick said the decrease in funding is one factor behind the rise in violent crime, along with violence being glamorised on social media and changes to the drugs trade.
A spokesman for the Mayor of London said: "This is desperate nonsense from the man who was in the government that slashed stop and search and funding for our police and preventive services and saw violent crime rise across the country.
"Sadiq is being tough on crime with extra money for the police and increased levels of targeted stop and search, as well as the causes of crime with money for youth services. But he has one hand tied behind his back - what City Hall can do is a drop in the ocean in the face of billions of pounds of Government cuts and the mayor makes no apology for calling for more money for our police."
Figures from the Office for National Statistics (ONS) show the number of "knife and sharp instrument offences" rose in the Metropolitan Police area from 13,341 to 14,159 between 2010/11 when Mr Johnson was mayor of London, but then fell for three years in a row to 9,680 in 2014/15.
Mr Johnson left office in May 2016 when he was succeeded by Mr Khan.
The ONS data shows an increase to 12,061 offences in 2016/17 and 14,695 in the following year.
The increase in offences recorded between 2015/16 and 2016/17 was 23.9%, while in England and Wales the increase was 19.6% over the same period, with all areas of the country except the North East seeing a rise in the number of offences recorded.