LONDON (Reuters) - John Lewis (JLP.UL), the employee-owned group viewed as a barometer of retail spending, posted a fall in weekly sales at its department stores, breaking a three week streak of positive sales.

The group, which also runs the upmarket Waitrose supermarket chain, said on Friday 14 August sales at its 27 department stores fell 5.3 percent to 45.4 million pounds in the week to August 8.

That followed rises of 5.6 percent, 6.3 percent and 5.3 percent in the three previous weeks.

Sales in the home category fell 7.2 percent, while fashion sales were down 2.8 percent and electricals and home technology fell 6.2 percent.

John Lewis blamed the sales fall on hot sunny weather on Saturday August 8, as its department stores traditionally do better at this time of the year if the weather is cool and unsettled.

"After a successful July, last week saw much thinner trade," said managing director Andy Street.

"It was not, however, a surprise as the warm sunny day proved more of an attraction to our customers after a few wet weekends. The change in weather revealed that our scores in July overstated our progress, and it is still a challenge to match last year's trade."

A raft of retailers from DIY group Kingfisher (KGF.L) and fashion chain Next (NXT.L) to grocer Morrison (MRW.L) and carpet seller Carpetright (CATVU.L) have reported better-than-expected trading in recent weeks, and on Tuesday 11 August the British Retail Consortium said underlying retail sales rose 1.8 percent year-on-year in July.

This had raised hopes of a rapid recovery from recession.

Sales at the 213-store Waitrose chain increased 10.9 percent year-on-year to 81 million pounds.

Conversely the weekend sun boosted Waitrose, particularly demand for barbecue and picnic food.

(Reporting by James Davey; editing by Rhys Jones)