The UK's school watchdog has no power to regulate 'age-inappropriate' sex education like 'gender unicorns' and 'anal sex', the head of Ofsted has warned.

Ofsted chief inspector Amanda Spielman said the regulator is currently powerless to sanction schools teaching inappropriate material to children as young as 12.

It comes after a Daily Telegraph investigation found some academies and independent schools were teaching pupils about 'gender unicorns' and asking children as young as 12 how they felt about anal and oral sex. 

Pupils in Years Seven and Eight at schools overseen by The Kemnal Academies Trust have been taught using a diagram of a 'gender unicorn' showing sliding scales of male, female and other identities, alongside spectrums of gender expression and sex assigned at birth.