Jan 14 - Sales at British department store chain John Lewis rocketed last week as shoppers rushed to buy furniture and electrical goods ahead of an increase in VAT sales tax.

John Lewis in Liverpool, UK

Employee-owned John Lewis, which also runs upmarket grocery chain Waitrose, said on Friday it also benefited from an extra day of holiday compared with the same week the year before, and from snow disruption the same time a year ago.

Department store sales leapt 38.7 percent year-on-year, the biggest rise in the group's fiscal year which ends this month.

Tesco, Britain's biggest retailer, on Thursday joined a string of store groups to blame bad weather for weaker-than-expected Christmas sales.

John Lewis, which has long outperformed the broader retail sector, has bucked that trend, helped by its more affluent customer base, which is coping better with rising taxes and government spending cuts than lower income groups.

The group said sales of home-related products leapt 42.9 percent, while sales of electricals and home technology goods were up 38.3 percent and fashions up 35.1 percent.

Online sales were up 42 percent.

VAT sales tax rose to 20 percent from 17.5 percent on Jan. 4 as one of a number of austerity measures by the government aimed at slashing its debts.

Weekly sales at Waitrose were up 2.9 percent year-on-year.

(Reporting by Mark Potter; Editing by David Cowell)