Children should not be taught to be patriotic at school, researchers said.
The Government has called for history lessons to help children develop a sense of their British identity and a love of their country.
But academics at the Institute of Education in the University of London warned that pupils should not be encouraged to love Britain for its "morally ambiguous" history.
The report, by Michael Hand and Jo Pearce, said patriotism should be taught - but as "a controversial issue".
Dr Hand said: "Gordon Brown and (Tory leader) David Cameron have both called for a history curriculum that fosters attachment and loyalty to Britain.
"But the case for promoting patriotism in schools is weak. Patriotism is love of one's country, but are countries really appropriate objects of love?
"Loving things can be bad for us, for example when the things we love are morally corrupt.
"Since all national histories are at best morally ambiguous, it's an open question whether citizens should love their countries."
The researchers questioned more than 300 teachers in London secondary schools and pupils aged 13-14.
Three-quarters of the teachers felt they had an obligation to alert their pupils to the dangers of patriotic sentiments. Only 9% of teachers thought schools should actively promote patriotism.
