Tesco has become embroiled in a legal row with rival the Musgrave Group, after it was accused of providing "false and misleading" information to an Oireachtas committee investigating supermarket prices.
In a series of legal letters, the Musgrave Group, which owns the Supervalu and Centra brands, claimed figures provided by Tesco to the Oireachtas Committee on Enterprise and Small Business, which showed Tesco to be cheaper than both Supervalu and Centra, were incorrect.
The group has asked that the figures be purged from the record of the committee and it has reserved its rights to take further legal action against Tesco on the prices.
Tesco says it stands over the figures it gave to the committee. "They are all based on detailed research and they stand up," a spokesman said.
A spokesman for Musgrave said the group was continuing to seek the "purging" of the figures from the record of the committee and was awaiting a response before deciding what further action to take.
In early November, in a presentation to the committee which is investigating retail prices, Tesco claimed that its detailed weekly surveys of 3,000 products showed Supervalu to be on average 5 per cent more expensive than Tesco, while Centra was shown to be on average 29 per cent more expensive across 500 items.
One week later, Arthur Cox, solicitors for Musgrave, sent a letter to Tesco stating: "Our clients believe that these figures are false, misleading and very damaging to its brands".
The letter demanded that Tesco divulge "immediately full and complete details as to how the statistics Tesco presented to the joint committee were arrived at.
"Furthermore our clients demand that there be no further publication or public discussion of these comparisons until the information requested has been provided and we have had an opportunity of considering the matter with our client."
Tesco's solicitors wrote back stating that the information was "statistically accurate and provides a proper reflection of price differentials". The letter refused to provide details of the research as it was "both internal and private" to Tesco.
In a subsequent letter, solicitors for Musgrave told Tesco that if it made price comparisons in public, "it should be prepared to back up its assertions in full and in public".
Tesco's solicitors responded that it would not provide the details as it was commercially sensitive and private.
Two days before Christmas, the chief executive of Musgrave, Mr Séamus Scally, wrote to the chairman of the Oireachtas committee, Mr Donie Cassidy, questioning the Tesco figures and claiming they did not tally with Musgrave's own research.
Musgrave claimed that its survey of 1,500 items, which were weighted to represent an average shopping basket, showed that Supervalu prices varied by less than 1 per cent with either Tesco or Dunnes Stores over a 12-week period to the beginning of October.
"In simple terms a consumer spending an average €150 a week on groceries could expect to spend a similar amount on a shopping basket irrespective of the brand of store," Mr Scally wrote.
He also claimed that prices in the Centra stores ranged from between 3 per cent and 14 per cent greater than average Supervalu prices, with the most expensive stores being in Dublin city centre convenience stores.