Labour's plan to impose VAT on private school fees could hit girls “harder”, an education chief has suggested.
Donna Stevens, chief executive of the Girls' Schools Association (GSA), said Labour's policy could be “damaging” to progress made on gender equality.
Addressing heads of girls' schools at the annual GSA conference in the Cotswolds on Monday, Ms Stevens highlighted “emerging political threats”.
Labor remains committed to its policy for England of charging 20% VAT on tuition fees and ending the business rate relief that private schools benefit from.
The head of the GSA told PA news agency: “My concern is that this policy would hit a disproportionate number of girls' schools and that would be detrimental to the progress we've made over the last 150 years in terms of equality.”
He warned there could be “more gaps in access to a girls' school” if private schools are forced to close as a result of Labour's policy.
Girls are disproportionately taught in the independent sector, which would mean female students are more likely to be affected by Labour's plans to scrap tax breaks for private schools, Ms Stevens suggested.
She said: “We want more choice for girls, not less.”
Rachel Reeves told the Labor party conference that she would use her first budget as chancellor of a Labor government to end “the tax loophole that exempts private schools from VAT and business rates”.
When asked about Labour's plans, Marina Gardiner Legge, principal of Oxford High School and chair of the GSA, told PA: “Girls' schools have a lot of parents where both parents are trying to struggle to pay the fees.
“We've had an increase in the cost of living and I think we're just concerned that a lot of parents won't have access and therefore won't be able to afford schooling for girls.
“All the research shows that this is the best thing for their daughters.”
Last month, Labour's shadow education secretary, Bridget Phillipson, hit back at critics of the party's plans to remove tax breaks from private schools.
The shadow education secretary was responding to reports in the Guardian from June which suggested that Independent Schools Council (ISC) officials had described Ms Phillipson as “very shrill” in private messages.
He said “high and rising standards cannot just be for families who can afford them” as he unveiled Labour's plans to reform early years education.
Julie Robinson, chief executive of the ISC, warned: “This policy would really affect those smaller schools with lower fees that are more accessible to normal working parents and families the most.
“It's usually families who for some reason can't get the kind of education they're looking for for their child locally, so they're willing to pay for it.”
Speaking to PA at the GSA's annual conference, Ms Robinson said: “If these schools close or if a percentage of their pupils move into the state system, that becomes a cost to the state sector.”
He added that disadvantaged children could be “further back” in the queue for top state schools if more middle-class parents – who previously paid for private education – sought state-sector places.
“Not only does it have a negative impact on the independent sector, I think more importantly, it has a negative impact on the government sector,” the ISC chief executive said.