John Lewis reported a “softer sales performance” over the week to July 28 as its first half sales soared 12.9%.

John Lewis managing director Andy Street said demand had been “sapped” by the opening of the Olympics and the hot weather.

Sales jumped 6.2% year-on-year, but its London Oxford Street store was down 8.7%. Its official London 2012 merchandise sales rocketed 86% over the week, which the department store said augured well for the week ahead.

Electricals, home and technology soared 22.9% while fashion edged up 2.8% for the week. Its menswear and sports department had an “excellent” week, which it attributed to the run-up to the Olympics. Home saw a small drop back by 1.8 %.

John Lewis’ first half sales have jumped 12.9% with electricals, home and technology leaping 30%, which it attributed to its “must-have” stock and constant innovation. Fashion advanced 7% over the half year with nursery and baby leading the growth.

Home also grew 6% while its online business soared 40%. The department store said improvements in fulfilment helped stimulate the growth and its click and collect business has doubled over the period, largely due to its tie-up with Waitrose where customers can pick up their purchases with their groceries.

Street said: “We go into the second half with confidence provided by strong momentum. We’re on course to sell huge quantities of London 2012 merchandise this week, which I’m sure will benefit indirectly from our small part in The Games; a remarkable achievement for our country.”

Waitrose sales for the week to July 28 were boosted by the sunshine and a celebratory atmosphere across the country, advancing 13.6%.

The grocer’s international sales experienced a jump. Waitrose products are sold in more than 30 countries and the retailer has 10 stores outside the UK.

Waitrose personnel director Helen Hyde said: “With all eyes on London at the moment, Waitrose has seen its international business build to its biggest ever trading period, with sales 35% higher than this time last year.”

Its top-selling products abroad are those offering a ‘taste of Britain’ , ranging from tea, biscuits, traditional sweets and preserves, to tins of beans and jars of gherkins.

Domestic sales received a boost from the hot weather, which stimulated picnics and barbeques over the weekend. Sparkling wine sales were up 75% year-on-year as Pimm’s sales soared 116%. Sunglasses sales jumped 43% year-on-year and it had its biggest ever week of ice cream sales, up 55%.

Waitrose said sales of its Food to Go range had doubled at its Westfield Stratford City store as Olympic spectators picked up something to eat on the way to events.