None of the main Russian television channels have carried reports about the arrest of a woman accused of killing a 4-year-old girl in her care and then waving the child's severed head outside a Moscow subway station.

Russian President Vladimir Putin's spokesman on Tuesday denied that the news was withheld at the request of the Kremlin or out of concerns that the brutal killing could stoke ethnic tensions in a country with many Muslims.

The suspect is a 38-year-old woman from Uzbekistan who some witnesses said shouted "Allahu akbar" while waving the head on the street on Monday. On videos posted on Russian news websites, she is heard shouting "I am a terrorist" in Russian.

Investigators said the woman, who appeared to be mentally unstable, was the child's nanny.