British police said they arrested a man after a stabbing in London's Leicester Square that left an 11-year-old girl needing hospital treatment and a 34-year-old woman with minor injuries.

The police said that the incident in the central London square, an area popular with tourists, was not being treated as terror-related.

Britain's police forces remain on high alert after days of riots earlier this month, which were triggered by false online posts wrongly identifying the suspected killer of three girls in northern England as an Islamist migrant.

The injuries of the 11-year-old victim were not life threatening, the police said, adding that she was being treated in the hospital.

There were no other outstanding suspects, police said.