LONDON (Reuters) - Sales at Wal-Mart's (N:WMT) British supermarket chain Asda (N:WMT) fell 5.1 percent in the 12 weeks to April 24, the worst performance in a period when all four of the country's big chains saw sales declines, industry data showed on Wednesday.
Market researcher Kantar Worldpanel said sales at market leader Tesco (L:TSCO) fell 1.3 percent, ending four months of improvement, while Sainsbury's (L:SBRY) and Morrisons (L:MRW) saw falls of 0.4 percent and 2.6 percent respectively.
Prices of groceries in Britain have been declining every month since September 2014 as the traditional market leaders fight competition from fast-growing discounters Aldi [ALDIEI.UL] and Lidl [LIDUK.L].
Sainsbury's, Britain's second biggest supermarket, reported a second straight year of profit decline earlier on Wednesday, and said it saw no let up in competition.
The fall in sales at Sainsbury's was the first since July last year, Kantar said.
"This marks the first time that each of the big four has simultaneously witnessed a drop in sales since April 2015," Kantar's Fraser McKevitt said.
Lidl remained Britain's fastest growing supermarket with sales up 15.4 percent, while sales at bigger rival Aldi rose 12.5 percent.