Fast fashion retailer QUIZ said online sales fell by 14.8% in the seven weeks up to January 4, in line with the broader retail sector's poor trading over the Christmas period.
The 27-year-old company trades online, in stores, through concessions and via third party sites.
It said tight cost control meant its overall performance in the year to date was broadly in line with its expectations however.
The Scottish based group said revenue from online sales via QUIZ's own website grew, even with less advertising than last year, but sales from third-party websites "declined significantly".
As a result group revenue in the period fell by 9.3%. Tight cost control meant gross margins were broadly in line with expectations.
In the past year the company has been reducing the number of unprofitable partnerships with third-party online sellers.
The number of people visiting its standalone stores and concessions has also gone down in the current financial year.
UK clothing retailers struggled over the Christmas period. Superdry and Joules issued profit warnings last week, and Marks & Spencer's reported weak menswear sales.
But online fashion retailer Boohoo outperformed its rivals when it reported robust Christmas sales earlier this week.
"While the trading backdrop remains challenging, it is disappointing to report a decline in revenues in the Period," QUIZ chief executive Tarak Ramzan said.