A spike in violent crime in London saw more murders committed in the city in February and March than there were in New York, figures show.
So far in 2018, 46 people in London have been fatally stabbed, shot or injured compared to 50 in the US city.
But, while New York’s rate month-on-month has decreased since January, London’s is on the rise.
Ex-Met Police Ch Supt Leroy Logan says it is proof that “London’s violent traits have become a virus”.
Statistics from the New York Police Department (NYPD) and the Metropolitan Police, reported in the Sunday Times and obtained by the BBC, highlight narrowing murder rates between the two cities which have similar population sizes.
City Hall says it is “deeply concerned” by knife crime in the capital, but, along with the Met Police, insists London “remains one of the safest in the world”.
The Met said it was “concerned at the increase in murders in London”.
“One murder is one too many, and we are working hard with our partners to understand the increase and what we can all do to prevent these tragedies from happening in the first place,” a spokesman said.
However, it is a murder rate that has left Mr Logan feeling “absolutely devastated”.
“I cannot understand how things have gotten out of hand,” he said.
“We have seen the virus of violence spreading. It is endemic in so many different parts of societies.
“It can only be dealt with in a holistic manner, because it is so holistic in its impact.
“Police can’t just arrest or stop and search their way out of this problem, it has to be done in partnership with the communities.”
In February, Met Police commissioner Cressida Dick visited police in Glasgow to learn about a public health approach which has seen murder rates in Scotland drop dramatically.
There are plans for Ms Dick to carry out more “fact-finding trips” in New York, as well as with the West Midlands, Durham and Avon and Somerset forces.
Meanwhile, the government has launched a £1.35m series of adverts to run across social media in a bid to deter 10 to 21-year-olds from knife crime.
The adverts feature stories of teenagers who have been stabbed.