By Ian Walker

LONDON--German discount grocers Aldi and Lidl continue to take sales and market share away from the big four in the U.K., though Tesco PLC's (TSCO.LN) market-share fall is the slowest in six months, suggesting it may return to growth this year, according to a market survey Tuesday.

Aldi and Lidl's joint market share rose to 10.7% in the 12 weeks ended Aug. 14, up from 9.7% in the comparable 12 weeks ended Aug. 16, 2015. Aldi's market share has risen to 6.2% in the 12 weeks, from 5.6% for the comparable period in 2015. Lidl's market share has risen to 4.5%, from 4.1%.

Aldi's sales in the 12 weeks have grown 10.4% to 1.55 billion pounds ($2.04 billion), while Lidl's have risen 12.2% to GBP1.14 billion.

Tesco's market share for the 12 weeks ended Aug. 14 stood at 28.1%, compared with 28.3% for the comparable 12 weeks, Kantar Worldpanel said. Kantar monitors the household grocery purchasing habits of 25,000 demographically representative households in the U.K.

Tesco's sales over the period are down 0.4% to GBP7.03 billion.

Fraser McKevitt, head of retail and consumer insight at Kantar Worldpanel, said: "Current trends suggest the retailer may return to growth this year, which would mark the end of a decline stretching back to March 2015. Tesco's recent product launches have been making a positive impact on its performance, with its 'farm brands' finding their way into over a quarter of the Tesco baskets this period."

Sainsbury PLC (SBRY.LN)'s market share in the 12 weeks ended Aug. 14 declined to 16.1%, from 16.3%, while sales fell 0.6% to GBP4.04 billion.

Asda, a subsidiary of Wal-Mart Stores Inc. (WMT), saw its market share fall to 15.7%, from 16.6% for the comparable 12 weeks, with sales 5.5% lower at GBP3.92 billion.

Wm Morrison Supermarkets PLC (MRW.LN)'s market share fell to 10.6%, from 10.8%, while sales dropped 1.8% to GBP2.64 billion

Up-market retailer Waitrose's market share was unchanged at 5.1%, and sales climbed 1.4% to GBP1.28 billion.

Write to Ian Walker at ian.walker@wsj.com

(END) Dow Jones Newswires

August 23, 2016 03:45 ET (07:45 GMT)