Discount chain Lidl is still the cheapest grocery retailer in the Irish Republic - with own-brand prices 20% below those of the main supermarkets, according to a survey by the National Consumer Agency (NCA).

The agency, a statutory body, also found that market leader Tesco’s prices had risen more in the past year than its main rivals’. A basket of branded goods at Tesco cost 4.9% more in January this year than it did in December 2007, while prices at Dunnes rose 3.4% and at Superquinn 2.3%.

On own-brand goods, Tesco’s prices rose 9.3% , double the amount of its competitors’. For a basket of 28 comparable own-brand items, Lidl was cheapest at €34.80, followed by Aldi at €36.18, Tesco at €40.59 and Dunnes at €42.20. However, Dunnes was the cheapest multiple on branded goods.

According to NCA chief executive Ann Fitzgerald, the survey found less price-matching by the three main chains - Tesco, Dunnes and Superquinn - than in the past, while prices at Lidl and Aldi were “almost identical”. The multiples, she said, were putting emphasis on own-brand goods to meet the challenge of the discounters, and there were some indications that in this area the price gap between them was narrowing.

She spoke out against the increasing number and range of special offers from the multiples, saying: “They may not always deliver the best value. We would prefer to see sustained price cuts.”