Ofsted has revealed that a snap inspection of the Mazahirul Uloom School in Tower Hamlets showed that a majority of pupils do not know the difference between Shariah law and British law.
In the first of six damning reports, the education watchdog added that pupils believed it was wrong to learn about other religions, as the school only focused on Islamic themes.
The report added that the pupils were also not taught art, music or drama as that does not fit in with the school's focus on Islamic teachings.
While there was no allegation around the school cultivating a Trojan Horse-style plot to spread conservative Muslim views, it did warn that children were not being protected from extremist views.
"We note that of the schools inspected, only one is a publicly funded maintained school," said Tower Hamlets council's director of education Robert McCulloch-Graham, who wasn't able to directly address the reports' findings before all of them have been published.
"As is common practice, we will work with the leadership of this school to address any issues identified by Ofsted.
"As a local education authority, we have no jurisdiction whatsoever over teaching and standards at independent faith schools. This is Ofsted's area of responsibility.
"We do, however, have responsibility for safeguarding all children in the borough and have always exercised our safeguarding duties to the full."
Ofsted implemented a series of snap inspections in October and the reports are the results of those investigations.