Gangs operating so-called county-lines drug networks are targeting private school children, as they are “less likely to raise suspicion”, the chief inspector of schools will say today.

The networks see urban dealers forcing children and other vulnerable people to courier illegal substances to customers in more rural areas, and Ofsted boss Amanda Spielman will use a speech in Manchester to warn of the issue.

According to the Daily Mail, she will tell the National Children and Adult Services Conference in Manchester: “Though children who have fallen out of education are likely to be targeted…all children, including those in areas of relative affluence, are fair game.

“We have heard of gangs targeting private school children, for example, because they are less likely to raise suspicion.”

Ms Spielman will also use the speech to say the lessons of previous scandals, such as the Rotherham sex-abuse cases, needed to be learnt.

She will say: “I am very concerned that, despite the hard lessons we have all learned from past failures to pick up child sexual exploitation, similar mistakes may be being made.”

Earlier this week, Ofsted warned that gangs were getting children to carry knives into zero-tolerance schools in order to get them excluded so that they could be “groomed”.