UK supermarket chain Morrisons has said its sales over Christmas were "disappointing", even after taking into account difficult market conditions.
It said that in the six weeks to 30 December like-for-like sales, which exclude new store openings, fell 2.5% compared with the same time last year.
Morrisons said the figures showed it needed to improve its promotions, the BBC reports.
It also said that they showed the importance of online shopping, which Morrisons does not offer.
"Notwithstanding these difficult market conditions, which we expect to continue through 2013, our sales performance in the period was disappointing," the retailer said in a statement.
"This reflects both the need to improve our promotional innovation and the communication of our points of difference... and the accelerating importance of other channels, such as online and convenience, which Morrisons has only recently entered."
Morrisons - the UK's fourth largest supermarket group - said that despite the disappointing six-week period it still expected its full-year results to be in line with its previous forecasts.
Morrisons is the first of the big four UK supermarket groups to report Christmas sales.
Rahul Sharma, director of retail consultancy Neev Capital, said Morrisons was also suffering from a resurgent Tesco.
"The fact is Tesco is throwing a lot of promotional money and using a lot of offers to bring people back into the stores," he told the BBC.