The Catholic Church is reluctant to invest in new free schools and academies because they will have to accept a large proportion of children from different backgrounds, a former minister has claimed.

Tory MP Mark Hoban said that senior figures within the church felt it was too easy for the schools they control to lose their religious focus.

Under the current rules, new faith-based free schools or academies must admit at least 50 per cent of their children from different religious backgrounds if they are over-subscribed.

But a parliamentary debate today heard that Catholic parents were known to pull their children out of schools if they lost their religious ethos.

Mr Hoban, a Catholic MP who has served as a minister in the Treasury and at the Department for Work and Pensions since 2010, urged the Government to lift the cap.

The MP said there were already 243 Catholic “converter” academies but lifting the cap would encourage the church to make further investments.

“Unfortunately, there is a cap on faith-based admissions, which inhibits the willingness of Catholics to sponsor a new academy or free school, and therefore limits the diversity of academies or free schools,” he said.

“There is requirement on bishops to decide where there is a demand for Catholic education, that this is satisfied. They feel it would be a breach of canon law to support a school that then turned away Catholic children.

“There is a broader point too about ethos. There is something very different about a Catholic school and its values. There are aspects of school life which are bound up in the sacramental life of the school - the participation in mass, a set of shared values, and the reference points that relate to the church and its teaching.

 “It is hard to see how you can maintain that shared set of values and ethos if half the pupils are unable to relate to the practice of the Catholic faith. That is not to say that these schools should be exclusively Catholic, and indeed three in 10 children at Catholic schools are not Catholic.

 “But the point comes where the dilution of a school’s Catholicity means it loses its ethos and it loses parental support. The faith-based admissions cap is a disincentive to Catholic Church and separate faith schools as it dilutes their ethos.”

Education minister Liz Truss admitted that many faith-based free schools and academies were over-subscribed, but defended the cap.

She said: “If the government funds new faith-school provision, it is right that a proportion of the places be available to the whole community, including those of other faiths and none.

“I acknowledge... that the Catholic sector has objections to our policy on admissions to faith-free schools. I know that the Catholic Education Service (CES) has been in discussion with department officials.

“We remain committed to continuing our engagement with the CES, although I point out that we have no intention of changing or removing the 50 per cent limit.”

The Catholic Education Service confirmed that it had been working with Mr Hoban to “bring the issue to the Department for Education’s attention”.

Richy Thompson, education campaigner at the British Humanist Association, which is a member of the Fair Admissions Campaign, said: “The Catholic Church seems to be the only religious organisation that’s refusing to take part because of the cap.

“The Catholic Education Service should be prepared to accept that by taking state funding they should serve the whole community.”