Schools will be able to allocate places by “lottery” to ensure fairness between all applicants and to stop middle-class families from dominating the best secondaries, under a new admissions code for England.

The mandatory code, which will come into force in September 2008, is being introduced to tackle “back-door selection”, where schools cream off the best students and pick pupils by social background.

Many of the best state schools have become largely the preserve of families who can afford to buy homes nearby or expensive uniforms or who can show their commitment to the school through generous donations.

Labour MPs demanded that the code be toughened during the revolt against Tony Blair’s school reforms last year.

Alan Johnson, the Education and Skills Secretary, said that the code would create a system where all children, regardless of their background, had a fair opportunity of gaining a place at the school they want to attend.

“[It] puts mandatory measures in place to ensure that this is the case at all schools, including the few schools that persist in using unfair or unnecessarily complex arrangements that can disadvantage some families and reduce the life chances of thousands of children,” he said.

Lottery systems, which are already common in countries such as the United States, could be used to counter the house price effect by giving children from all backgrounds a chance to enter a draw for places.

“Random allocation of school places can be good practice, particularly for urban areas and secondary schools,” the code states.

“It may be used as the sole means of allocating places or alongside other oversubscription criteria. Random allocation can widen access to schools for those unable to afford to buy houses near to favoured schools and create greater social equity.”

However, it adds that the practice might not be suitable for rural areas, where schools draw children from a wider geographical area and where children who did not win a place through the lottery draw might otherwise have to travel a considerable distance to an alternative school.

A spokesman for the Department for Education said that lottery systems were most likely to be used to allocate places left over after the use of other admissions criteria, such as distance or membership of a faith group. They could be open to challenge by local parents who lost out for not benefiting the local area, he added.

The code will also ban covert forms of selection such as requirements for expensive school uniforms, sportswear or costly trips, unless arrangements are put in place to ensure that parents on low incomes can afford them. It will also ban admission interviews.

Comprehensive schools will still be allowed to operate sibling policies, which allow children automatically to follow older brothers and sisters into the school.

However, in the case of the 39 partially selective state schools, which select more than 10 per cent of pupils, the schools must ensure that their admission arrangements do not exclude families living nearer the school.

Sarah Teather, the Liberal Democrat education spokeswoman, said: “This new tighter code is welcome, but it will only make a difference if it is rigorously enforced. Heads and governors must realise that they will not get away with ignoring or flouting the new rules.”

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