The Bush administration has announced proposals for America’s largest government-sponsored private school voucher scheme just days after its own survey found that state schools do as well as or outperform private schools.

Margaret Spellings, US education secretary, was accused of placing ideology before sound policy by pushing vouchers in contradiction to the findings released by her own department. Adding to the political embarrassment, she confessed that she had not read the report, which bears her name and singles out Conservative Christian private schools as “significantly”

trailing state schools academically when English language status and race are taken into account.

Conservative Christian private schools are among the biggest participants in voucher schemes already operating across America.

The proposed $100 million (pound;54m) Opportunity Scholarship programme would be the first national roll-out. That its name scrupulously avoids the v-word is a gauge of the contention vouchers stir up in US education circles.

Low-income students at schools failing to achieve testing benchmarks six years running would be eligible for annual grants of $4,000 (pound;2,163) towards private school fees.

Proponents say vouchers offer educational equity to pupils right now, rather than waiting for school-level reform efforts to take effect.

They say by targeting pupils at chronically-underperforming schools, which might be years from getting their act together, they are giving students a shot at the same start in life their wealthier peers are able to pay for.

Ms Spellings said: “Sixty-two per cent of Americans make choices about which community to live in because of the quality of schools. But it’s not right for those who can’t (afford this) to be trapped in schools that don’t perform.” Vouchers also inject vital competition into public education, spurring state schools to raise their game in an education marketplace in which students and parents may vote with their feet if they are not satisfied, supp-orters say.

A 1,500-pupil study following a local scheme in New York between 1998 and 2002 found African-American voucher recipients narrowed the achievement gap on their white peers by one-third. It sought to control for a distorting “selection effect” in which voucher students may be more motivated in the first place than their peers in state schools, by comparing those given vouchers in a random lottery with those missing out in the same lottery.

But opponents see vouchers as a right-wing hobby horse that drains money from state education.

Christopher Lubienski, assistant education professor at the University of Illinois, said the US education department report, which looked at scores on common reading and maths tests taken at ages nine and 13 across more than 6,900 state schools and 550 private schools, undermines the premise of vouchers by “undercutting assumptions that private schools are the superior model”.

It shows that “private schools get better results largely because of the students they’re dealing with”, said Mr Lubienski, who published similar findings last year.

In absolute terms, private schools handily outscore state schools, the report found, but when gender, ethnicity, special needs status and English language competency were factored in, state schools were largely level-pegging or had an edge.

Grover Whitehurst, director of the US education department’s research arm, the Institute of Education Sciences, said: “It indicates that private schools are serving a slightly more advantaged population than (state) schools and that, when you adjust for that, differences tend to be diminished or disappear.”

But he cautioned against reading too much into the findings as far as the vouchers debate goes, noting it was limited to a “snapshot in time”, student performance on a single exam - rather than educational progress - and didn’t look at “low-performing” state schools, from which voucher students would come.

STATE VERSUS PRIVATE

The US education department’s comparison of state and public schools in America found:

* On US-wide reading and maths exams taken by nine and 13-year-olds, state schools held their own and even narrowly outperformed their private counterparts on all counts except 13-year-old reading scores.

* Taking into account students’ gender, ethnicity, special needs diagnoses and whether they were native English speakers, maths scores in Conservative Christian schools were “significantly lower” than those in state schools.

* Also adjusting for student variables, Lutheran denominational schools had “substantially” higher maths scores than state schools, markedly better than other private schools.