Tesco has retained its position as the country's biggest grocery retailer with a 25.1% share of the market, despite a sales decline of 3.3%.
The latest supermarket share figures from Kantar Worldpanel, for the 12 weeks ending 21 June, show that the supermarket has increased its volume of items bought, as shoppers take advantage of savings and stock up on goods.
But this has not been enough to compensate for a decrease in shopper numbers and average spend.
Overall, the figures show a year-on-year growth in sales of 0.9% across the market.
Dunnes Stores overcame the effects of a one-day strike by workers on 2 April to show a 6.3% growth in sales over the 12 weeks to 21 June.
The company’s market share reached 22.2%, up from 21% the same time last year.
Only Lidl outperformed Dunnes Stores, with market-leading growth in sales of 6.4%.
SuperValu sales grew just behind the market at 0.6% and its share remained flat at 24.7%.
Approximately 19,000 fewer shoppers visited the retailer than over the same period last year and those that remained were more frequent but lighter shoppers, visiting SuperValu more often but picking up fewer items on each trip.
Aldi, with 8.5% market share, and Lidl, with 8.7%,continued to recruit shoppers to their stores and household penetration is now at 63.1% and 65.1% respectively - ahead of Dunnes' 63%.
However, the growth in shopper numbers at discounters is slowing. Aldi gained 28,000 new shoppers in the past 12 weeks compared with 80,000 this time last year, and Lidl picked up 6,000 - down from 53,000 in the 12 weeks to June 2014.