Muslim parents in Batley, West Yorkshire, are refusing to allow their children to attend religious education classes because they are insufficiently Islamic.
In the biggest mass exercise of its kind to date, more than 1,500 junior school children have been withdrawn from RE lessons in 40 schools - a procedure specifically allowed under the law. It is understood that the withdrawal started at the beginning of term after advice from local Islamic scholars.
According to Ibrahim Hewitt, development officer with the Association of Muslim Schools, the parents are concerned that RE is taught by non-Muslims; that it may be inaccurate about Islam; and that it may confuse young Muslims by introducing them to other faiths.
The dominance of Christianity in the RE syllabuses has been an anxiety. "We're not saying that they should not learn about other religions, but that it should be within an Islamic context," said Mr Hewitt.
In a press release, the parents said: "Matters of religion are of a sensitive nature, particularly when children are concerned."
A spokesman for Kirklees local education authority said its officials will meet community representatives to discuss ways forward.