Iran’s supreme leader has blamed the US and Israel for the anti-government protests sweeping the country, in his first public comments on the unrest.

Ayatollah Ali Khamenei said “riots” had been “engineered” by Iran’s arch-enemies and their allies, and alleged that Qurans had been burned.

He also called on security forces to be ready to deal with further unrest.

The protests – the biggest challenge to his rule for a decade – were sparked by the death in custody of a woman.

Mahsa Amini, 22, fell into a coma hours after being detained by morality police on 13 September in Tehran for allegedly breaking the strict law requiring women to cover their hair with a hijab, or headscarf. She died three days later.

Her family has alleged that officers beat her head with a baton and banged her head against one of their vehicles. The police have said there is no evidence of any mistreatment and that she suffered “sudden heart failure”.

Women have led the protests that began after Ms Amini’s funeral, waving their headscarves in the air or setting them on fire to chants of “Woman, life, freedom” and “Death to the dictator” – a reference to Ayatollah Khamenei.