The spiralling cost of everyday essentials is forcing consumers to cut back on what they buy in the shops and to substitute expensive items such as beef for cheaper alternatives such as chicken, experts have said.

The new figures come at a time when many families were forced to spend more to meet the demands of the return to school. Worldpanel said shoppers had been taking advantage of price promotions in shops, spending €758m on promotional lines during the latest 12-week period, an increase of 8.2pc on the previous year. Promotional spending now makes up 21.5pc of all grocery sales.

Households with children made greater use of online shopping in the last few weeks, spending an additional €6.6m compared with the previous month. Nearly 18pc of Irish households bought their groceries online during this time.

With many parents preparing for the new term, store visits increased by 0.7pc, although shoppers picked up fewer packs per trip.

Overall, shoppers spent an additional €68.8m on groceries compared with the same period last year.

Emer Healy, business development director at Worldpanel by Numerator, said: “As the new school term began in early September, we saw spending on typical lunchbox staples increase across many households with children.”

She said that over the latest four-week period, shoppers had spent an additional €5.3m on sweet bakery items, fresh fruit, breakfast cereals and porridge, savoury snacks and yoghurt.

“Convenience is also a priority, with an extra €1.6m spent on fresh and frozen ready meals and cooking sauces compared with last year,” Ms Healy said.

Households with children also made greater use of online shopping, spending an additional €6.6m compared with the previous month.

They also added €1.2m more to their baskets on sliced meats, yoghurts, breakfast cereals and biscuits as they stocked up for school lunches.

The growth in the purchasing of brands has slowed, but shoppers still spent an additional €62.6m on branded products.

Own label had stronger growth at 6.6pc, with premium own label the standout performer, up 16.2pc.

Dunnes holds 23.9pc market share, up on the last 12-week period, with slowing sales growth of 6.1pc year-on-year, according to Worldpanel.

Tesco holds 23.7pc of the market, with value growth of 6.4pc year-on-year.

Shoppers increased their trips to stores by 1.3pc and, together with new shoppers, contributed an additional €23.7m to the grocer’s overall performance.

SuperValu holds 19.5pc of the market with growth of 4.9pc.

Consumers made the most shopping trips to this grocer, averaging 24.7 trips over the latest 12 weeks, up 9.6pc year-on-year.

The increase in shopping trips contributed an additional €61.6m to its performance.

Lidl holds 14.2pc of the market with growth of 9.5pc, the fastest growth among all retailers.

Lidl shoppers also picked up more volume in store, up 2.5pc, contributing an additional €11.5m to overall performance, Worldpanel said.

Aldi holds 11.6pc market share, up 4.7pc. Increased store trips and new shoppers drove an additional €16.1m in sales.