Tesco "seriously" breached an industry code by intentionally delaying payments to suppliers, a long-awaited report by the Groceries Code Adjudicator has said.
A long-awaited report on the supermarket giant's practices revealed it had "intentionally delayed" paying suppliers "in order to improve its own financial position".
One supplier was owed a multimillion-pound sum because of price changes being incorrectly applied to Tesco systems.
The money was eventually paid back by Tesco more than two years after the incorrect charging had started, said the Adjudicator.
GCA Christine Tacon said she found delay in payments arising from data input errors, duplicate invoicing, deductions to maintain Tesco's margins and unilateral deductions.
"The sums were often significant and the length of time taken to repay them was too long," she said.
Her 84-page report said Tesco had breached the legally binding code aimed at protecting groceries suppliers.
Ms Tacon launched the investigation last February following Tesco's announcement about its profit overstatement.
Ms Tacon made a series of recommendations to stop the practices, saying the retailer should be more transparent in its dealings with suppliers.
No financial penalty was imposed because this power was only given to the Adjudicator after she launched her investigation.
Tesco has been given a four-week deadline to say how it plans to implement the recommendations.
Dave Lewis, Group Chief Executive Officer for Tesco, said the supermarket accepts the report's findings, which are consistent with their own investigation.
Tesco said it had reviewed the way it works with all of its 3,000 UK suppliers and as a result, implemented "14 significant initiatives to improve the way it works with suppliers and how it runs its business".