Trading standards officials at the home authorities for Asda, Morrisons and Somerfield said cases of mislabelling were common and covered “varying degrees of severity”.
However, officials also said prosecutions were rarely brought as problems were often dealt with promptly by the companies affected.
The revelation follows a report in a Sunday newspaper that Tesco had more than 20 cases of suspected product mislabelling between December 2004 and January 2005.
Over the same period, Asda had 16 reported cases and Morrisons 17 reported cases, one of which included Asda chicken breast fillets containing 13% water, contravening EU rules stipulating that chicken breasts with added water and other ingredients should not be labelled as fillets.
Suspected mislabelling cases at Tesco raised by Hertfordshire Trading Standards included a 500g pack of frozen lamb mince with traces of pork, a chicken baton sandwich that contained 57% more salt than was stated on the label, and an apple and kiwi drink that contained significantly less added vitamin C than was stated on the label.
A Tesco spokesman said: “We’re looking into all of the cases but this must be kept in proportion. I think there were a couple of prosecutions last year. But when things go wrong, they are dealt with.”