A dispute has erupted over the place of religious education in the revamped state exam to be sat by school-leavers at the end of the month.

For the first time, the exam includes a continuous assessment component, worth up to 20 per cent of the final mark. But teachers are finding it hard to establish criteria for awarding the marks.

The decision by teachers at a school in Pavia, near Milan, to give one mark to all candidates who had attended a course in religious studies has caused howls of protest, and led to a threat by Republican party leader Giorgio La Malfa of a vote of no-confidence in the education minister, Luigi Berlinguer.

Protesters say the “bonus point” discriminates against pupils who opt out of religious studies and violates the Italian constitution.

The problem is that religious studies is a non-compulsory curricular subject - in essence it is a weekly one-hour lesson in Catholic doctrine, and is attended by most pupils. But parents can withdraw children if they wish and final-year students over 18 can themselves opt out.