Tesco knowingly delayed paying money to suppliers in order to improve its own financial position, the supermarket ombudsman has found.
The Grocery Code Adjudicator has said the supermarket giant breached the industry's code of conduct by delaying payments to suppliers.
Tesco has apologised for the practices. It is still under investigation by the Serious Fraud Office (SFO) over alleged accounting irregularities.
The Grocery Code Adjudicator's investigation began in February 2015 after revelations of an accounting scandal at Tesco. In September 2014, a £250m black hole was found in the company's accounts - a sum later revised up to £326m - because of the way Tesco booked income from its suppliers .