A nanny accused of decapitating a young girl in her care before brandishing the head in a Moscow street says she heard voices from "Allah" ordering the killing as a judge extended her detention during a first court appearance.

Prosecutors told the court that they believed there were other individuals who had "incited" her to carry out the beheading and they are still at large. The nanny from Uzbekistan is expected to be charged with murder later this week.