Walmart's (WMT) - Get Report U.K. division, Asda, has been ranked the worst grocery store in the country, according to a consumer survey, with its online offering not faring much better.

Consumers ranked privately-held Waitrose as the best place to buy food in Britain because of its quality and easy-to-navigate stores, according to a survey of 7,004 Britons conducted by consumer advocacy magazine 'Which?'.

Marks & Spencer (MAKSY) came a close second due to the quality of its own-label and fresh food products while Asda ranked last with the grocery chain seen as having good value food but with only average quality.

"We know that we need to do a better job for our customers and our colleagues are working hard to make a real difference," an Asda spokesperson told The Guardian.

Asda also came joint last for its online offering with Sainsbury's (JSAIY) and Waitrose, a placing that will likely embarrass Walmart, which agreed to buy for $3 billion last year in an effort to improve its online offering to compete with Amazon(AMZN) - Get Report  .

Consumers ranked privately-held discount supermarket Iceland as the best online supermarket due to its value for money and convenient delivery slots while online-only supermarket Ocado (OCDDY) ranked second.

Morrisons (MRWSY)  , which recently extended its partnership with Amazon to provide same day delivery to Prime customers, placed third.

M&S stock was up 0.5% at 332.3 pence at 10:30 GMT but have lost 2% over the past three months against a 1.18% advance for the FTSE 350 Food and Drug Retailers Index.

Morrisons stock was down 0.6% at 247.30 pence at 10:15 am GMT. Shares have gained 13.2% in the past three months. Ocado stock was down 0.62% at 257 pence, extending its 0.35% loss over the past three months.

Asda, which is the No. 3 supermarket in Britain with a market share of 15.6%, has been losing ground for some time in the U.K. to low-cost rivals.

Walmart said that to contend with the fall in shares and market share it will throw its weight behind the division.

Walmart said it will ensure Asda, which has 630 locations across the U.K., leverages its parent's purchasing strength, allowing it to buy everything from refrigerators to own-brand products to real estate for a cheaper price driving down costs, Walmart's chief administration officer, Scott Price, told Reuters.

"One thing that maybe we would criticize ourselves for is that we didn't start the repositioning of the business sooner, that we didn't focus more on the leverage opportunities so that Asda was able to invest more aggressively in price," Price told Reuters.

The new strategy will allow Asda to stock Walmart brands "put an Asda brand on it that is equal to the national brand in the U.K. in terms of quality and sensory, but at a price that no one can match," Price said.

Walmart shares closed at $68.69 Wednesday, little-changed on the session but down 3.89% over the past three months.