High street retailer Next - which has more than 20 stores in Northern Ireland - has warned that full-year profits could suffer after sales for the first quarter fell 0.9%.
Sales at the chain's high street shops plunged 4.7% as it pointed to March and April's cold weather dampening demand for its clothing.
The company also said the lacklustre figures could indicate a wider slowdown in consumer spending.
"The poor performance of the last six weeks may be indicative of weaker underlying demand for clothing and potentially wider slowdown in consumer spending," Next said.
Sales at the Next Directory catalogue business also slowed, coming in at 4.2%.
Next cut its annual full-price sales guidance to between minus 3.5% and plus 3.5%, also warning that pre-tax profit could fall by as much as 8.9% to £748m.
Its estimate at the higher range is a 3.7% rise to £852m.
While Next said that this week's better weather had seen an improvement in trading, it nevertheless warned that it is possible that "sales will deteriorate further".
Chief executive Simon Wolfson warned in January that 2016 would be challenging after the firm reported a sales slump over Christmas.
Julie Palmer, partner and retail expert at Begbies Traynor, said: "Previously an example of stability in an otherwise rocky UK retail sector, Next has without doubt hit a rough patch, announcing its third cautionary statement in a row.
"Adding to its woes, Next has failed to maintain the support of its historically loyal shareholder base, with the group's share price plummeting more than 30% since the start of the year, as investors seemingly took their profits and ran.
"Worryingly, the upcoming EU referendum could further dampen the retailer's spirits as both consumers and investors alike take a more cautious approach to their finances ahead of the Brexit vote."
The latest figures for footfall in Northern Ireland, showed shopper numbers dropped even further as spring failed to bounce life back into the retail sector.
The figures collected by the Northern Ireland Retail Consortium showed footfall was down by 1.5% year-on-year for the five weeks between February 28 and April 2.
However, the UK average drop in footfall was even more dramatic, falling by 2.7% year-on-year.