Sue McMahon from Calderdale, west Yorkshire, where the fascist party has three local councillors, said children as young as nine had been recruited by the BNP which was circulating race-hate leaflets in schools.

Teacher Bryan Beckingham told the NUT conference that every time the BNP leafleted his Birmingham school, race incidents broke out between Asian and white pupils.

In Llandudno, the NASUWT voted to campaign to change the law so that it could stop members of far-Right groups infiltrating the union. BNP activists were raising funds by joining unions so they could be excluded and then win compensation, the conference heard.

Chris Lines, chair of the NASUWT’s equal opportunities committee, said: “Do we want our members’ subscriptions to pay for peddling messages of hate in this country?”

Katie Rowley, a religious education teacher from Wakefield, said she had found RE books at her school defaced with racist remarks.

The NUT also voted virtually unanimously to oppose bans on wearing the hijab in England and Wales. Lawrence Wong from east London said: “It is stupid to say that the hijab is the symbol of women’s oppression in Europe when Islam is the religion of an oppressed minority.”

Jean Roberts from Hammersmith and Fulham spoke on behalf of the minority who disagreed, saying: “School is not a place for practising religion.”

Samidha Garg, NUT principal race and equality officer, told journalists that the union was working on guidelines that schools could use when pupils wanted to wear the hijab.