The mystery of the low-flying helicopter has been solved - it was an RAF chopper in training.
According to the RAF press office, it was a Merlin Helicopter from RAF Benson.
A spokeswoman said: "It would have been on a routine or training sortie."
RAF Benson is based near Benson in South Oxfordshire.
The helicopter was seen swooping low over the Leicester city centre before flying off across the county.
Residents in the Welford Road and Clarendon Park areas of Leicester, as well as Oadby all reported spotting the helicopter.
Aaron Carter's video of the chopper near De Montfort University