Parents who pay for their children to go to private schools could be leaving them "marooned on an island of privilege that does not reach out to the mainland", the head of Ofsted has said.
Speaking at the Sunday Times Festival of Education, Sir Michael Wilshaw called for independent schools to do much more in partnership with local state schools, saying they had a "moral obligation" to bring an end to their "splendid isolation".
He praised the apparently few schools, like Eton and Wellington, that have sponsored an academy or free school, but said that most others had refused the Government's suggestion to do so.
Sir Michael picked out individual educators for criticism, asking why Repton School in Derbyshire had set up a boarding school in Dubai when children living 20 minutes away only have a 50/50 chance of getting into a successful primary school.
The comments follow on from a particularly poor set of recent Ofsted reports into the performance of comprehensive schools, and he said that: "A fundamentally unequal society is no good or any of us in the long term."
Saying he was "issuing a direct challenge to independent school heads", Sir Michael offered a list of ways more privileged schools could help their counterparts.
Private schools should invite the brighter children from state schools to attend their science lessons, he said, as well as provide them extra tuition and interview coaching at top universities.
He recommended they also help train teachers for comprehensive schools, and encourage staff to become governors in the state system.
He said: "And to those who say, 'parents pay £30,000 a year for the privilege', I'd ask if they really want their children marooned on an island of privilege that does not reach out to the mainland?"
He added that: "The conferment of privilege should not denote exclusivity, but an implied duty to help the wider community."
The comments have sparked anger from the private school sector. Charlotte Vere, executive director of the Girls' Schools Association, tweeted: "So disappointed Wilshaw hasn't a clue about independent-state partnerships. 90 per cent of independent schools involved. Don't attack, collaborate."
And Matthew Burgess, the general secretary of the Independent Schools Council, said Sir Michael had "treated the audience to a headline-grabbing speech", but seemed to be "unaware of basic facts".
"Sir Michael appears disappointingly out of touch with the breadth and depth of participation activity between the sectors," he said.