* Week to Jan 19 department store sales up 6.7 pct
* Says sales lost momentum as snow started falling
* Week to Jan 19 Waitrose sales up 6.3 pct
LONDON, Jan 25 (Reuters) - John Lewis has become the first British retailer to caution that last week's snow hit sales growth.
Britain's biggest department store group, said on Friday its sales rose 6.7 percent to 59.5 million pounds ($94 million) in the week to Jan. 19, having grown 18.7 percent in the previous week - the final week of its post-Christmas clearance sale.
"The underlying trade remained very strong and we were +15 percent going into Friday. However, our momentum chilled somewhat as the first significant fall of snow in almost a year hit Wales and much of England," the firm said.
Though sales of electricals and home technology rose 29.6 percent, driven by demand for tablet PCs, sales of fashion and homewares were down 6.8 percent and 1.7 percent respectively.
Online sales were up 40.3 percent, showing how resilient that channel can be during bad weather.
Howard Archer, chief economist at IHS Global Insight, said the latest John Lewis data "highlights the very real risk that the disruption to the economy from the snow and ice could be enough to cause the economy to contract modestly in the first quarter of 2013 rather than grow."
With Britain facing the prospect of a triple-dip recession, many retailers have been finding the going tough as consumers fret over job security and a squeeze on incomes.
John Lewis has bucked the gloom because its generally more affluent customers have been less impacted by Britain's economic downturn, while improvements to product and service and new modern stores have chimed with consumers.
The group also owns upmarket grocer Waitrose. Its sales increased 6.3 percent to 108.2 million pounds in the week to Jan. 19.