The mayor of London, Sadiq Khan, has been urged to consider a gun crime strategy for the capital, following a steep rise in the number of offences and fears that victims and perpetrators are getting younger.

The Metropolitan police recorded 2,542 gun crime offences in 2017, the highest number in five years and 44% more than the 1,755 recorded in 2014, according to a report by the London assembly’s police and crime committee.

In a letter to Khan, Steve O’Connell, the Conservative member who leads the committee, called for more research into where guns come from and what is driving their use, as well as a commitment to publish more detail on gun crime in London.

“The question for you and for [the mayor’s office for police and crime] is whether gun crime, in the same way as knife crime, requires a distinct and specific approach to prevention and intervention, and one that focuses more widely than gang activity,” he wrote.

Meanwhile a 21-year-old man was in a life-threatening condition in hospital on Monday after being shot in the head in east London on Sunday night. Police found the man on Romford Road, Newham, after reports of a shooting just before 10.30pm. Detectives were investigating, but no arrests had been made by early Monday evening.

About a third of the victims of gun crime and almost three in five offenders were aged 25 or under in the 12 months to October 2017, according to the assembly’s report. There were anecdotal suggestions from police and a senior trauma doctor that they were seeing younger victims than in the past.

Drug dealing and gang activity were identified as the main drivers of gun crime, with gangs said to account for nearly half of all offences where lethal guns – as opposed to non-lethal airguns or stun guns – were fired.

The report also raised concerns about weapons or weapons parts being bought online through encrypted “dark web” marketplaces. The supply of weapons from eastern Europe was said to be a growing concern.

“The supply of guns from abroad being aided by new technology is a trend that needs to be stopped in its tracks,” O’Connell said. “The changing nature of gun possession and use will also need careful monitoring and may prompt the need for a change in the approach to intervention.

“And the worrying trend that both offenders and victims of gun crime are getting younger means we must provide more information to young people about the consequences of carrying a gun, and what to do if they find one or are aware of someone possessing one.

“What we cannot do is allow it to evolve into the kind of situation the capital faces with other serious violence, most notably knife crime.”