The new president of the National Union of Teachers, Baljeet Ghale, says that plans to teach Britishness would fuel racism
Speaking at the same conference, a leading black academic claimed that the plan would play into the hands of the far-Right.
Professor Gus John said any attempt to teach British values would be "fatuous", and he claimed all schools must assume they are institutionally racist.
Their comments triggered a furious response yesterday, with one prominent Tory branding them lunatic and offensive.
Earlier this year, ministers announced that they would include 'core British values' in secondary school citizenship classes to promote better community relations.
Pupils will study aspects of British history and discuss openly their sense of national identity.
Education Secretary Alan Johnson wanted schools to promote values such as "free speech, tolerance and respect for the rule of law".
But Mrs Ghale, the NUT's first ethnic minority president, told its conference in Harrogate that there was nothing in the stated values which wasn't specifically British.
In her keynote speech she said: "I have no doubt that for some behind notions of what it means to be British stands the shadow of racism.
'For them this is not about integration, participation and pride in the country in which you live but more about a failure to assimilate or indeed who should be here in the first place.
"To demand that people conform to an imposed view of Britishness only fuels that racism.
"We must never forget that racism is not always overt but is multifaceted, often subtle and sometimes without malicious intent.
"All too often racism is used to scapegoat individuals or groups by those who want to cover up their own shortcomings, inadequacies and prejudices - including our own politicians and political leaders."
Professor John, of the University of Strathclyde, added: "I would like someone to define what British values are. I want nothing at all to do with the values of the BNP which are quintessentially British."
However Tory MP Douglas Carswell, a member of the Commons education select committee, said: "The fact is that the July 7 terrorists blew up their citizens.
"These are people who have been born in Britain, raised in Britain and supposedly educated in Britain. At no point did they feel any sense of solidarity and ownership with their fellow Britons.
"This is a major issue that now needs to tackled. This lunatic politically- correct suggestion that inculcating a sense of Britishness is somehow racist I personally find offensive.
"It is not a credible position for anyone in public life to have."
He said pupils should learn "our island story" as well as "universal" values such as freedom of speech.
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Britishness lessons 'fuel racism'