Rank-and-file police officers have reacted with fury to suggestions by the chancellor, Philip Hammond, that forces should move resources to prioritise tackling knife crime.

The row erupted after the second fatal stabbing in 24 hours in London, in which a teenage boy was attacked in West Kensington and later died in hospital. The death came after 26-year-old David Martinez died following an attack in Leyton on Wednesday.

Police chiefs have been seeking at least an extra £15m after the home secretary, Sajid Javid, said the government should listen to their demands.

Hammond had already rebuffed Javid’s call for extra funds at a cabinet meeting on Monday and did so again in broadcast interviews on Thursday. Speaking to BBC Breakfast, he said the government had already agreed to almost £1bn in extra policing resources in the next financial year, and he urged forces to use existing money more efficiently.

“If all police forces operated at the level of the most efficient in terms of eliminating paperwork and the most modern ways of mobile working, we’d save enough police time to be the equivalent of about 11,000 additional officers a year,” he said.

He also urged police forces to prioritise knife crime by redeploying officers from other areas. “Today we are focused on knife crime, and rightly so, but there are many other demands on available public spending. My job is to make sure that in dealing with an issue like this we use public resources in the most effective way.

“We know from polling that people consider tackling knife crime should be the number one priority. So I want to see police forces surging officers from other duties into dealing with knife crime, nipping this problem in the bud early and making sure we turn this spike around.”

John Apter, the chair of the Police Federation, which represents tens of thousands of police officers, said: “It amazes me that the chancellor is still prioritising balancing his books over tackling this national emergency. Children are dying on our streets and he has the audacity to suggest that the police need to prioritise. Let me assure him, this is a priority.

“Across England and Wales, my members are the ones working flat out to prevent more young people being killed. They are often the ones on their knees in the street trying desperately to save the lives of these young victims, they are the ones who have to deliver the terrible news to families that their loved one will never be coming home again. And they are doing it with almost 22,000 fewer colleagues than when the Conservative government came to power.

“It is an insult to my dedicated and hardworking colleagues, and it shows a shocking lack of awareness or understanding of the reality of the crisis happening right now in towns and cities across the country.”

David Jamieson, the police and crime commissioner for the West Midlands, said: “The reality is that knife and gun crime have risen sharply both here and across the country. After a decade of cuts the thin blue line is now thinner than ever.

“I would ask the chancellor what police operations he wants us to stop doing in order to tackle violent crime. Would he prefer West Midlands police to do less to tackle child sexual abuse, domestic violence or terrorism? I eagerly await his response.

“The chief constable has quite rightly prioritised the response to knife crime in our area, but that effort hasn’t been without significant cost.”

Police chiefs have warned school pupils they could face up to two years in jail if they continue gossiping online about the killing of the Manchester Grammar school pupil Yousef Makki.

Senior officers have circulated letters marked ‘‘urgent’’ to schools and colleges urging students not to post messages about the killing of 17-year old Yousef, and telling them their social media chatter could interfere with the murder trial.

It is believed the prime suspect’s family has been subjected to abuse, and social media accounts belonging to the boy’s mother and older sister have now been deactivated.

The 17-year-old boy accused of the murdering Yousef in a knife attack was given bail in a hearing at Manchester crown court on Thursday.