Tesco has reclaimed the top spot in grocery market share for the first time in more than two years, according to figures from Kantar Worldpanel.
The supermarket has an overall share of 22.3% after its sales grew by 4.5%.
The gap between the top three has widened, with SuperValu and Dunnes capturing 22.0% and 21.8% of the market respectively.
Key to Tesco's success in becoming Ireland's biggest grocer once again, has been its strategic emphasis on volume sales, particularly through its private label offering.
"While value sales are robust, growing at 4.5% on last year, volume performance has been even stronger," said Douglas Faughnan, consumer insight director at Kantar Worldpanel.
"Tesco's own label range has been at the centre of its performance, now accounting for more than half of overall sales following double digit growth this period," he added.
SuperValu sales grew by just under 1% this period achieving an overall share of 22%.
Kantar Worldpanel said the retailer’s focus on fresh produce through its "SuperValu 7" offer is evident - volume sales of vegetables are up on last year with staples like tomatoes, potatoes and carrots showing particularly strong performances.
Dunnes has seen an increase in customers coming through its doors for the first time in more than 12 months. Dunnes saw an extra 9,000 shoppers in the last 12 weeks. This, combined with a 3.4% increase in average price paid and shoppers buying more items per trip, helped the retailer grow by 2.6% compared with last year.
Branded sales have been helping boost discounter performance, according to Mr Faughnan.
"Combined, private label items at Aldi and Lidl still account for over 90% of sales, but both retailers have expanded their branded ranges to attract shoppers and encourage more spend from existing customers.
"Branded sales at Aldi now account for 7.6% of overall sales, up from 6.5% in 2017, while 11.1% of Lidl’s sales are from branded items, compared to 8.6% at the same time last year. These increases have been central to the overall growth of 2.0% and 3.5% at Aldi and Lidl respectively," he said.
The introduction of the sugar tax in Ireland on May 1 has not yet been reflected in volume sales of carbonated soft drinks - overall volume sales in May were up 4.8% on the same period last year.
However this did coincide with a period of hot weather over the early May bank holiday, where other drinks categories like mineral water and fruit squash also experienced a volume increase.
Although the tax is in its infancy, there is a substantial level of awareness among Irish shoppers about its existence - 50% say they are aware of it and that it is important to them.