Girls are being coerced into group sex in the belief it is “normal” behaviour as exploitation worsens in gangs, an official Home Office report warns today.

The study, which also discloses that children aged below nine have joined gangs in London, quotes a report from experts about “cornered” girls having sex with up to five gang members.

It suggests other “vulnerable” female gang members are being exploited without realising they have been victims of rape or other sexual abuse.

Girls are also used by gangs to store drugs and firearms and set up “honeytrap” attacks on rival gang members.

The warnings came as the Home Office unveiled a six-point plan for tackling gangs. The measures include protecting children in care homes and pupil referral units from being “targeted” by gang members.

Renewed efforts will also be made to stop gangs waiting outside schools to recruit pupils, while further measures to divert vulnerable children into education, training and jobs are pledged.

In the report published today on urban gangs in 19 London boroughs and 14 local UK authorities, ministers warn that there is “more involvement in gangs by young people (aged nine to 14) now compared with two years ago”.

The report, compiled from evidence by police and other officials working to tackle gangs, also says even younger children are in London gangs. It further warns of the “use of young, often vulnerable, people to transport drugs to other parts of the country”, with children given “targets for selling” and punished if these are not met.

Some youngsters are recruited with the “lure of earning money or being given new trainers, tracksuits” and other items, with some absent from school or care homes for days during their illicit smuggling missions.

An increase in knife-carrying and stabbings is also reported in some parts of London. Nearly half those questioned from the capital said the size of gangs has increased. Most boroughs studied are thought to have more than 100 active gang members.

The report says drug dealing by gangs is widespread, with violent crime, robbery and sex attacks the other most common activities. It adds that London gangs are becoming more multi-ethnic and says: “Sexual violence and exploitation by gangs has worsened.”

It quotes one person involved in tackling London gangs saying: “You get the guys talking of having group sex with vulnerable girls. Then you’ll have the girls talking about it as well but both will refer to it as though it was a normal thing. If you were to suggest it was rape or exploitation, they’d be horrified.”

Unveiling today’s report, Home Office minister Karen Bradley said funds for anti-gangs work would be extended to Harrow in addition to existing London boroughs covered by the programme.