Schools in England will be required by the government to actively promote fundamental British values to their pupils, both in lessons and in extracurricular activities, according to new documents published by the Department for Education.

The guidance significantly hardens the language used in setting out how schools teach what is known as spiritual, moral, social and cultural (SMSC) development, replacing the previous language of “respect” for British values with the requirement to actively promote them.

The DfE document says pupils should be taught “how democracy and the law work in Britain, in contrast to other forms of government in other countries”, and advises teachers to “consider the role of extracurricular activity, including any run directly by pupils, in promoting fundamental British values”.

According to the document: “Actively promoting the values means challenging opinions or behaviours in school that are contrary to fundamental British values. Attempts to promote systems that undermine fundamental British values would be completely at odds with schools’ duty to provide SMSC.”

John Nash, the schools minister, said in a statement: “We want every school to promote the basic British values of democracy, the rule of law, individual liberty, and mutual respect and tolerance for those of different faiths and beliefs. This ensures young people understand the importance of respect and leave school fully prepared for life in modern Britain.”

The new rules are likely to set the DfE into further conflict with faith schools, including Catholic, Jewish and Muslim schools, because of its clear requirement that they give priority to secular law rather than religious teachings.

Similar revised guidance for independent schools was published simultaneously.

The document states that each school’s “ethos and teaching, which schools should make parents aware of” should support English law. “If schools teach about religious law, particular care should be taken to explore the relationship between state and religious law. Pupils should be made aware of the difference between the law of the land and religious law,” it warns.

Recent requirements for all schools, including faith schools, to promote equality and diversity have drawn a hostile reaction from faith schools. The Catholic Education Service recently made a veiled protest over gay marriage: “We expect Catholic schools to teach factually about civil marriage alongside the promotion of the Catholic understanding of marriage.”

Recent Ofsted inspections have faulted a range of schools, including a Catholic secondary school in Suffolk and well as Jewish and Muslim schools, for failing to “prepare pupils for life in modern Britain” and not adequately teaching inclusivity and tolerance.

The new document also states that teachers are expected to “uphold public trust in the profession and maintain high standards of ethics and behaviour, within and outside school. This includes not undermining fundamental British values.”

The guidelines also respond to critics of the promotion of British values by providing greater detail as to what the DfE defines as British values and how they should be taught.

According to the document, pupils should be expected to have “an understanding of how citizens can influence decision-making through the democratic process” and “an appreciation that living under the rule of law protects individual citizens”.

Schools will be expected to “use opportunities such as general or local elections to hold mock elections to promote fundamental British values and provide pupils with the opportunity to learn how to argue and defend points of view”.

Russell Hobby, general secretary of the National Association of Head Teachers, said: “The majority of schools will find they have been ‘actively promoting’ British for years. Our advice for most members is: don’t do anything new, make sure you capture and describe the good work you are already doing.”