LONDON (Reuters) - Britons are placing growing importance on fresh and quality foods, boosting sales at grocers Wm Morrison, J Sainsbury and Waitrose but hitting Asda, according to industry data.

Market researcher Kantar Worldpanel said yesterday grocery sales rose 4.3 percent in the 12 weeks ended September 5, helped by a 2.7 percent rise in grocery price inflation.

"While uncertainty in the economy means that value is still important, consumers are placing increasing importance on the freshness and quality of the food they buy," said Edward Garner, communications director at Kantar Worldpanel.

"This is evident in the premiumisation we have seen in the grocery market and the strong performances of Sainsbury's and Waitrose."

Waitrose, part of John Lewis, saw a 9.3 percent rise in sales growth over the same 12 weeks a year ago, while Sainsbury gained market share for the 19th straight month with growth of 5.5 percent.

Morrison, also known for its focus on fresh foods, saw sales rise 5.9 percent, while Tesco, Britain's biggest retailer, broadly held its ground with growth of four percent.

Industry No.2 Asda (part of Wal-Mart Stores Inc) however lost ground for a ninth straight month, with sales growth of 2.6 percent. The chain has also been held back by the fact it is opening fewer stores than most of its rivals.

"Recent statements from Asda's chief executive Andy Clarke show that the retailer has recognised the need to adjust its strategy and we've started to see a greater emphasis on quality in the latest advertising campaign," Garner said.