Ocado has shrugged off the threat of a widely expected new year price blitz by Tesco and Sainsbury’s as it posted a near-15% rise in fourth-quarter sales this week.

Chief financial officer Duncan Tatton-Brown insisted the group continued to outperform the rest of the market in terms of online growth and would remain competitive in 2015.

The online supermarket has stepped up its promotional activity in recent times, including a basket-matching price scheme running a direct comparison of ­customers’ shopping against Tesco.

“The majority of baskets for customers are cheaper at Ocado,” the finance chief added. “Our customers know we are competitive and will remain so whatever the activity is.”

Ocado announced on Thursday that sales growth slowed during the fourth quarter to 14.9% compared with 15.5% growth in the previous quarter. Gross group turnover, including its partnership with Morrisons, rose by 18.6% to £331.9m.

Average orders per week soared 16.4% to 177,000, which Kantar Retail attributed to penetration into new geographies opened up by its second fulfilment centre. However, average basket size shrank again, by £2 to £109.74, as shoppers shifted towards own-label products.

Tatton-Brown said he looked forward to 2015 with “some confidence,” adding: “Although the market will remain challenging, we believe the quality of our proposition will mean we can continue to grow sales slightly ahead of the online grocery market.”