Russian police have arrested and charged a nanny with the murder of a girl, 4, in her care after footage was published online of a hijab-clad woman brandishing a severed head on the streets of Moscow.

Investigators said in a statement the unnamed nanny was from Central Asia and that she was undergoing psychiatric testing to see if she was mentally sound and understood the significance of the charges against her.

A woman in a black robe and black headdress was filmed near Oktyabrskoye Pole train station on the Tagansko-Krasnopresnenskaya in northwest Moscow on Monday (AEDT) holding what appeared to be a human head. In the video uploaded to the internet, she can be seen pointing one finger in the air — a Muslim symbol.

The New Daily has chosen not to republish the graphic footage.

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Employees of the Russian Investigative Committee collected evidence at the scene. Photo: Getty

The nanny charged with murder has been identified by Russian media as Gyulchehra Bobokulova, originally of Uzbekistan. Police will allege she is the woman seen in the video, and that the ‘head’ she brandished is that of the four-year-old child she was paid to babysit.

There are unconfirmed reports that the woman was shouting “Allahu Akbar” (Allah is Great) and “I’m a terrorist” and threatened to possess a bomb. The New Daily was unable to verify this from the available footage.

A newswire service interpreted part of the video as the woman screaming “I am a terrorist, I want your death” and talking about the end of the world while holding the head.

The woman allegedly waited for the parents to leave with their older child before she murdered the younger girl, set fire to the family’s apartment and took to the streets, according to Interior Ministry spokesperson Yulia Ivanova.

In other footage available online, Russian police can be seen tackling a burka-clad woman to the ground, reportedly outside Oktyabrskoye Pole station.

The nanny allegedly set fire to the damaged apartment seen here. Photo: Getty

The victim’s mother, named as Ekaterina, was filmed by Russian media being driven away in an ambulance in a state of distress after the incident.

There is as yet no claim from Russian officials that the child’s beheading was terror-related.

If the incident is linked to terrorism, and not isolated crime, it would mark one of many such incidents in recent years in Russia, which has upwards of 16 million Muslims. Attacks are especially rife in the North Caucasus region.

The most infamous terrorist attack in the Russian capital was the Moscow theatre siege in 2002, during which at least 130 hostages and 40 Islamic militants were killed.