Sexual exploitation and radicalisation are also key areas of concern, the force said.
Recruiters can loiter on street corners and approach children walking to and from class offering them a chance to “make some quick money”, a specialist said.
Others may be groomed over a period of months either in person or online.
DI Bediako Ahenkora, of the Met’s specialist crime unit, shed light on the matter in an exclusive interview with the Evening Standard.
The detective leads one of five investigation teams targetting serious organised crime, modern slavery and child exploitation.
“Those who want to exploit children look for those who are vulnerable,” he said.
“There are different ways of being recruited. It could be location based where they are approaching young people in the street.
“It’s not just care homes and schools but any places such as taxi ranks and fast food joints where they are known to congregate.”
Once enlisted some children go on to recruit their peers and expand the network, the detective explained.
He added: “Online is another means of recruitment through social media as a key avenue.”
As many as 4,000 teenagers are being criminally exploited in London alone and children as young as six forced to carry and sell drugs, according to the Children’s Society.
DI Ahenkora, who studied a Master’s in criminology at Cambridge University, told of the main socioeconomic factors which make young people vulnerable to exploitation.
This includes living in care, being excluded from school, poverty and deprivation, social isolation, behavioural difficulties, bullying and low school attainment.
“Covid may have changed vulnerabilities for young people too,” he added.
“In terms of schooling, for some young people the gap in attainment has increased as a result of lockdown.
“So we are not just looking at the crime that is taking place but trying to understand all the factors that lead into that.
“The other thing to think about is how London is changing, how our communities are changing and being mindful of events that then effect the make up of a city.”
What is being done?
The Met works with universities, charities and local authorities to develop their understanding and divert children away from crime.
In some cases where criminals are recruiting in a particular area, social services may accompany children to and from school and officers patrol neighbourhoods as a deterrent.
Shop owners in target areas might also be advised on warning signs and how to support children at risk.
“It is about educating wider society about exploitation to ask questions and be curious,” DI Ahenkora added.
Education is a key preventative with many programmes running across the capital.
Second Wave Youth Arts in Deptford is one example focusing on how to stay safe online and combat online grooming.
Operation Anzen in Newham has been successful in diverting young people from exploitation, specifically in working with social services to run risk assessment and escort children.
In Lambeth and Southwark, Dwaynamics Boxing Club organise events for youths at risk which are designed to steer them away from gang culture, knife crime and gun violence.
Barriers can occur between children and police due to trust issues, fear of reprisals and trauma.
“This is why we have to work with the community and people can get the support they need,” the detective added.