Woman 'waving around severed head of young child' arrested in Moscow

Police in Moscow have reportedly arrested a woman who was waving around the severed head of a small child outside a subway station in the Russian capital.

Graphic video footage posted on Russian news websites and YouTube show the woman dressed all in black and shouting "I am a terrorist," although most of what she says is incomprehensible.

The Investigative Committee released a statement saying a woman was arrested on suspicion of killing a child aged three or four in an apartment near the metro station in north-western Moscow, and then setting the apartment on fire.

The statement said the woman was believed to be the nanny.

The investigators said the woman appeared to be mentally unstable.