TESCO "seriously" breached an industry code by delaying payments to suppliers, the Groceries Code Adjudicator (GCA) has found.

Christine Tacon's long-awaited report on the supermarket's practices revealed it had "intentionally delayed" paying suppliers and also made "unilateral" deductions.

She has 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 that power was only granted after the Adjudicator began her investigation.

Tuesday's 84-page report said Tesco had breached the legally binding code aimed at protecting grocery suppliers.

Ms Tacon said: "I found that Tesco knowingly delayed paying money to suppliers in order to improve its own financial position.

"The length of delays, their widespread nature and the range of Tesco's unreasonable practices and behaviours towards suppliers concerned me.

"I was also troubled to see Tesco at times prioritising its own finances over treating suppliers fairly."

One supplier was owed a multimillion-pound sum because of price changes being incorrectly applied to Tesco systems.

The Adjudicator said the money was eventually paid back by Tesco more than two years after the incorrect charging began.

Ms Tacon launched the investigation last February following Tesco's announcement about its profit overstatement.

The Adjudicator said: "I saw numerous instances when data input errors by Tesco into its systems resulted in suppliers being overcharged or underpaid.

"Tesco failed to rectify data input errors within a reasonable time and also failed to pay money owed to suppliers as a result of these errors within a reasonable time."

The investigation found some Tesco buyers were reluctant to engage into disputes to resolve payment issues.

"There were times when Tesco did not appear to even attempt to resolve supplier concerns before unilaterally deducting money from suppliers.

"I found the delay that resulted from a failure by Tesco to fully engage in resolving difficulties to be unfair and unreasonable."

Business Minister Anna Soubry said: "Tesco say they have changed their practices and I very much hope they have. Paying smaller suppliers on time and treating them fairly is good and proper business. Late payment can hinder the growth and productivity of these suppliers and can threaten their existence."

Ms Tacon's recommendations include:

o stopping Tesco from making unilateral deductions from money owed for goods supplied. Suppliers will be given 30 days to challenge any proposed deduction and if challenged Tesco will not be entitled to make the deduction.

o the company corrects pricing errors within seven days of notification by a supplier.

o Tesco told to improve its invoices by providing more transparency and clarity for suppliers and to put its finance teams and buyers through training on the findings from the Adjudicator’s investigation.

Tesco has four weeks to say how it will implement the recommendations.

Dave Lewis, group chief executive, apologised and said: "In 2014 we undertook our own review into certain historic practices, which were both unsustainable and harmful to our suppliers. We shared these practices with the Adjudicator, and publicly apologised. Today, I would like to apologise again. We are sorry.

"We accept the report's findings, which are consistent with our own investigation. In January 2015, we made material changes to our business that addressed the majority of the historic practices referred to in the report.

"We have changed the way we work by reorganising, refocusing and retraining our teams and we will continue to work in a way which is consistent with the recommendations."