Parents face possible court action for withdrawing their children from lessons on gay and lesbian history.
More than 30 pupils were pulled out of a week of teaching at a primary school which included books about homosexual partnerships.
The controversial content was worked into the curriculum at George Tomlinson School in Waltham Forest, East London.
The council has declared that children who missed the lessons will be viewed as truants.
The ruling means some families could breach rules that children should not be absent for more than 19 days a year.
Sanctions include spot fines, parenting contracts and ultimately court action.
The parents, who objected to the lessons on moral and religious grounds, said the content was more appropriate to secondary age pupils.
Pervez Latif, whose children Saleh, ten, and Abdur-Rahim, nine, attend the school, said he knew of up to 30
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