A Primark customer found a human bone inside a sock bought in the store.
The customer made the shocking find after buying the item from the chain's Colchester station.
An Essex policeman said: ''Detectives are continuing to investigate following the discovery of what is believed to be part of a human bone in a pair of Primark socks.
''The bone does not appear to be a result of recent trauma and had no skin or other particles surrounding it.''
In a statement, the company said it was ''highly probable'' the bone was placed in the socks by a person.
The company said: ''Primark clearly takes this matter very seriously and has already carried out an investigation at our supplier's factory where the socks were made.''