Asda has announced a 2.6% decline in like-for-like fourth quarter sales but remains focused on delivering its long-term plan, which includes opening 17 new stores in 2015.

CEO Andy Clarke said that although the retail market remained “in one of its most challenging and changeable periods in history”, the supermarket group would invest £600m in expanding and improving the store estate this year.

In addition to the new stores, this will include remodelling 62 stores to reflect changing shopper habits, and creating 150 new remote click and collect stores.

Clarke said: “2014 saw an acceleration in the structural shift in the market and while we saw it brewing and put the right plan in place to address it, the pace and scale of change has exceeded all expectations.

“The first year of the plan was very much about building the foundations - a work out to limber us up for what is to come in 2015 - by leading the price agenda in a deflationary market. We have a clear plan for sustainable, profitable growth.

“I’m pleased that we can announce our continued investment in the UK with £600m for new and improved stores in 2015. With such a powerful force like Walmart behind us that fully supports our strategy, we’re in a unique position in a difficult market - a position of great strength.”

For the 2014 financial year, Asda posted a 1% fall in like-for-like sales.