John Lewis & Partners has suffered a slump in sales during the last full week before Christmas as retailers bank on a late festive shopping surge.

The department store chain posted a 5.1% drop in revenues in the week to December 21 compared to a year ago.

Sister retailer Waitrose & Partners’ sales plummeted 11.9% over the same seven-day period.

As a group, the John Lewis Partnership’s sales fell 8.7% to £381.6m.

The eponymous department store chain suffered its steepest sales declines in fashion and electricals and home technology, which fell 5.1% and 8.9% respectively.

Sales of homewares inched down 0.3%, but John Lewis’ furniture and flooring category grew 4.1%, boosted by its Clearance Sale.

John Lewis blamed the decline in revenues on “the effect of a strong Black Friday”, which fell after the November pay day this year.

The retailer added that online orders increased towards the end of the week after it extended its deadline on click and collect orders to Christmas Eve.

Waitrose, meanwhile, insisted its figures were “heavily skewed by the fall of Christmas” this year. In 2018, December 22 – one of its peak trading days – fell in the equivalent trading week.

Home and general merchandise revenues slumped 13.4%, while sales from its core chilled, fruit, veg, meat, fish, frozen, dairy and bakery categories tumbled at a similar rate of 13.3%.

Ambient sales dropped 9.8% year-on-year during the same seven-day period.

Despite the sales declines, Waitrose insisted that its online business was “performing strongly”. The number of orders placed to arrive in the week leading up to Christmas grew 22%.

Waitrose added that a “significant proportion” of those orders had been placed by new customers.