Teachers' children should not be allowed to jump the queue for places at the most popular schools, a leading educational charity has warned.
The Sutton Trust said the Government's planned overhaul of admissions rules would entrench inequality, and that preference should be given instead to children from poorer backgrounds.
A draft of the new admissions code, published in May, gives any oversubscribed school the discretion to prioritise the offspring of its teaching and non-teaching staff over other local children. The "family-friendly" policy is intended to help successful schools recruit and keep the best teachers.
But the Sutton Trust, which campaigns for social mobility through education, warned it would be a powerful disincentive for teachers working in more challenging schools in deprived urban districts.
A guarantee of places for their children at high-performing schools - often in expensive catchment areas - would draw teachers away, the charity said.
"Our fear is that it will become even harder to attract the best teachers to the most challenging schools," said Sutton Trust chairman Sir Peter Lampl.
Other controversial reforms in the draft code include allowing oversubscribed schools to expand at the expense of less popular institutions nearby. Sir Peter said that if successful schools want to take in more pupils, children from poor families should be first in line to benefit from any extra places.
"While we support good schools expanding, we are concerned that schools would tend to recruit more affluent students," he said.
"A solution would be to make expansion conditional on giving first preference to all children eligible for free school meals before allowing other children to take up the extra places. This would ensure that successful schools with the appetite to grow would recruit the pupils who would most benefit."
He added: "Allowing schools to give preference to children from disadvantaged backgrounds is crucial if pupil premium funding is to operate truly as an incentive for schools to actively recruit children from poorer homes."
The Department for Education's consultation on the proposals closed last week.
Education secretary Michael Gove has said allowing successful schools to expand will put pressure on underperforming schools to improve.
He also said the slimmed-down code lessens the bureaucratic burden on schools and makes admissions more transparent.
But critics say the reforms benefit the sharp-elbowed middle classes, and children from poorer families will be left behind in failing schools that will be starved of funds as enrolment figures plummet.
Unions and campaigners have branded the new code "weak" and warned that relaxing admissions rules could lead to "covert selection and segregation" as schools cherry-pick pupils from affluent families.