As many as 6,000 pupils may be faced with the threat of extremism at illegally operating schools in the United Kingdom, according to the latest figures released by British schools watchdog today.
In the past 15 months, Ofsted inspectors have identified 241 suspected illegal schools in England, The Sunday Times reported.
These include Islamic, Jewish and Christian faith schools as well as secular centres set up to teach pupils with behavioural difficulties who have been excluded from mainstream education.
The sites used by such schools include warehouses and old factory buildings.
More than 140 of the suspected illegal schools have not been inspected and no criminal cases have reached court, though two were considered for prosecution, the report said.
Most of the schools remain open and more than half have not yet been visited by inspectors, prompting fears that some children are at risk of radicalisation.
There are also fears that children are being taught by adults whose backgrounds have not been vetted.
When an unregistered school is identified in Britain, local councils are supposed to write to parents with children there but Ofsted fears some councils are failing to do that.
"We continue to investigate the remaining and will take all necessary action to close these down," said an Ofsted spokesperson.
Piyush Goyal and Jonathan Reynolds tour the Royal Opera House in London
