Consumers ordered fast food as well as their shopping online over Christmas, pizza delivery firm Domino's revealed as it reported strong sales growth.

In line with the trend seen in the retail sector, Domino's said one-fifth of online business now came from customers using mobile devices such as smart phones and tablet computers, compared with 10% a year ago.

Its online sales rose 56.6% to £84.1 million in the UK and Ireland in the 14 weeks to December 30, a figure that included £2m of sales in a single day for the first time. E-commerce now accounts for 55.7% of deliveries in the UK, compared with 44.3% in 2011.

Across the business, system sales rose 20% to £174.5m in the period, although the improvement was helped by an extra trading week this year. Like-for-like sales in 612 mature UK stores grew by 5%, in line with the trend seen over the rest of the year.

The group holds the master franchise to own, operate and franchise Domino's Pizza outlets in the UK, Ireland and Germany, having opened its first UK store in Luton in 1985. It acquired the German franchise in April 2011.

Chief executive Lance Batchelor said the company had delivered solid results in a tough trading environment. He added: "Our like-for-like sales growth in our core UK market has been good and we have opened a record number of stores."

It has opened 69 new stores, 57 in the UK and Ireland and 12 in Germany.