Islamic fundamentalism that encourages children to despise British society is being promoted on websites at some Muslim schools in the UK, think tank Civitas has revealed.
It warns the messages are threatening social cohesion and could fuel "ghettoization" and segregation.
A site linked to one primary school said playing Monopoly or chess was forbidden and likened the latter to "one who dips his hands in the blood of swine".
Another warned children in Britain were being exposed to a culture that was against everything Islam stands for, while a third school's website had electronic links to alleged extremist sites.
Others had links to other sites or chatrooms that contain fundamental views such as forbidding the playing of cricket or even reading of Harry Potter books.