Britain's only Sikh comprehensive has told parents that their children will have a better chance of getting in if they make a donation to a place of worship.
Guru Nanak Sikh secondary, a voluntary-aided school in Hayes, west London, may be the first state school in England to link, in its prospectus, pupil admissions with cash payments.
The revelation threatens to intensify the row between backbench Labour MPs and the Government over admission rules.
However, the school said that the advice simply illustrated a traditional Sikh method of demonstrating commitment to the faith.
An annex to Guru Nanak's 20056 prospectus lists six criteria by which pupils will be selected. Because the school is so heavily oversubscribed, it says that only those satisfying the first - that their parents or guardians prove their "deep commitment to the Sikh faith" - are likely to be accepted.
It then advises parents to "leave nothing to chance" when demonstrating that devotion.
As a minimum, parents should get a priest to fill in a form testifying to their commitment.
They were also strongly advised to provide other evidence, including support for a Sikh place of worship, a Gurdwara.
This could be done through "either financial or other donations", or other forms of Sewa (service); proof of attendance at the Gurdwara, or evidence of having supported the school or the trust which runs it.
Ranjinder Singh Sandhu, head of Guru Nanak, said "supporting the school"
should not be taken as meaning financial support, but that parents should show they had, for example, attended religious festivals at the school.
Admissions forms also state that the school does not accept donations during the admissions process.
Sikhs can fulfill the demands of Sewa, which translates as "selfless service to others", in three ways: by doing physical good work; by teaching children in the faith; and through financial donations.
But Professor Anne West, a school admissions specialist at the London School of Economics, said the stipulation could mean that children from poor families were disadvantaged over admissions.
Keith Porteous Wood, director of the National Secular Society, said: "The school almost seems to be putting a price on entry to what is an entirely publicly funded institution. If that's the case, that's unacceptable."
Other schools have faced criticism for the lengths parents must go to demonstrate religious commitment.
At Canon Slade, a voluntary-aided Church of England comprehensive in Bolton, parents and children must have four years' church attendance over at least 45 Sundays a year.
Mr Sandhu said Guru Nanak was reviewing its admissions policies to reserve places for non-Sikhs.
He said that it had more pupils from poorer backgrounds than other local schools.