A row has broken out over accusations that a British National Party activist has been told to teach only white pupils.
The NASUWT union has written to Derby council after complaints by local members about Clive Jones who stood as BNP candidate in a recent by-election for East Staffordshire borough council.
Chris Keates, NASUWT general secretary, said Mr Jones, a teacher at Derby City pupil referral unit, had been taken away from classes containing ethnic minority pupils. She said: "If this information is correct it serves only to provide an even greater opportunity to promote bigotry and does nothing to protect pupils from exposure to the vile agenda of this organisation."
A spokeswoman for Derby council disputed the NASUWT's claims. She said: "It has been brought to our attention that a BNP candidate in a recent by-election is currently working at the city's pupil referral unit. We are looking into a complaint from the NASUWT and will make a further statement."
About 10 per cent of the 200-plus pupils at the unit, which takes boys and girls aged five to 16, are from ethnic minorities.
Mr Jones was defeated by 150 votes by Dilpazir Ahmed, Conservative candidate, on June 29.
Ms Keates has written to Alan Johnson, the Education Secretary, asking him to stop BNP and National Front members working in schools and to allow unions to bar them from joining.
She said: "I understand this is not going to happen overnight. But with the rise of the BNP in local elections this is extremely important for the future of our public services."