Key religious figures have teamed up with atheists in urging the government not to drop the 50% cap on admitting children into faith schools because of their religion.

The Archbishop of Canterbury Dr Rowan Williams, the chief executive of Humanists UK, Andrew Copson and the scientist Richard Dawkins are among those who have signed a letter which warns that the Conservative policy of dropping the cap would harm social cohesion.

Under the present rule, oversubscribed, newly-established religious schools must keep at least 50% of places open to people who do not necessarily hold that faith.

But the Tory manifesto commitment to abolish this has been backed by the education secretary Damien Hinds. While the Catholic church has argued to lift the cap, the Church of England says it does impact what it does.

But in a letter to the Daily Telegraph, leaders say that the the Government must ensure that schools are environments of mutual understanding.

"The duty of the education system, therefore, should not be to highlight and entrench such differences in the eyes and minds of young people, but to emphasise instead the common values that we all share.

"Removing the 50 per cent cap on religious selection at faith-based free schools runs entirely counter to this ambition," said the letter which was also signed by Caroline Lucas, co-leader of the Green Party and around 70 other politicians and academics.