As many as 800,000 secondary school pupils are not being taught religious education, in spite of a legal obligation by schools to teach about major systems of religion and belief.

The failure raises 'serious implications for community cohesion and inclusivity', according to the National Association of Teachers of RE (NATRE).

Analysis of the Government's School Workforce Census shows more than one in four state secondary schools are struggling to meet their legal obligation to teach pupils about major religions and systems of belief.

This means teenagers are being deprived of vital knowledge about different faiths and beliefs in community, public and world affairs.

All state-funded schools, including academies and free schools, are legally required by the 1998 School Standards and Framework Act to provide Religious Education as part of a balanced curriculum.

Research by NATRE and the Religious Education Council, including a survey of 790 secondary schools, found more than one in four of all schools surveyed said a weekly RE lesson to ensure pupils understand different religions and beliefs is not available.

In academies and free schools, where RE is determined as part of the funding agreement, this figure rose to 34 per cent for 11 to 13 year olds, and 44 per cent for 14 to 16 year olds. Even four per cent of schools with a religious character do not offer a weekly lesson.

NATRE's Research Officer, Deborah Weston, said: 'Today, it is important to be religiously literate and to understand and question the accuracy of claims about different religions. RE provides for critical exploration of individual beliefs and values, while opening up the discussion about religion and belief in the communities we live in.

'These figures are alarming as they provide statistical evidence of a trend we have been hearing about from RE teachers, and come at a time where respect and tolerance for others' beliefs is essential.'

Rudolf Lockhart, chief executive of the Religious Education Council of England and Wales, said: 'More than ever, as our society becomes multicultural and religious extremism dominates the news agenda, we need young people to be religiously literate. We have been encouraged by an improved profile and better understanding for RE in schools from policy makers at both Ofsted and the Department for Education. They have committed to paying closer attention to RE, which makes these new statistics about schools' struggling to provide required levels of RE all the more alarming.

'RE knowledge is vital in ensuring all school leavers go into the world of work and beyond, understanding the differences, identifying distortions and being part of the broader change needed to ensure communities are cohesive and well-integrated for future generations.'