LONDON - John Lewis, Britain's biggest department store firm, has blamed Andy Murray's Wimbledon triumph, the first Ashes test in cricket and a heat wave for keeping shoppers out of its stores last week.

The employee-owned firm said on Friday week to July 13 department store sales fell 8.7 percent year-on-year to 64.2 million pounds ($97.6 million).

"The week started with Andy Murray clinching the Wimbledon title, which meant that all those who were not out in the sunshine spent the afternoon indoors watching the tennis," John Lewis said.

"From Wednesday onwards sport lovers had the first of the Ashes test matches to watch ... So with the festival of sport and with the most glorious heat wave weather it was not surprising to see a heavy deficit on trade from last year."

Sales of homewares fell 13.2 percent, fashion sales were down 7.3 percent, while sales in the electricals and home technology category were down 3.6 percent.

John Lewis has been outperforming the wider market for about three years but traditionally does better in poorer weather when consumers are focused on indoor pursuits.

Official data on Thursday showed British retail sales rose in June, the latest sign of a gradual recovery in the economy.

Conversely last week's very hot weather was good news for Waitrose, the upmarket grocer also owned by the John Lewis group. It saw sales soar 14.0 percent to 123.5 million pounds.

Waitrose benefited from shoppers stocking up on food and drink for dining outdoors. The firm said it had a record week for barbecue meats with sales up 200 percent year-on-year, while charcoal sales rocketed 720 percent.

($1 = 0.6579 British pounds)