Sainsbury’s has reported underlying first-half profit rose 5.4% to £373m.

Like-for-like sales including VAT and excluding fuel rose 1.7% while total sales climbed 4% to £13.4bn in the 28 weeks to September 28.

Sainsbury’s attributed the performance to strong new product development in own label – where it is 85% through a refresh of 6,500 ‘By Sainsbury’s’ lines that will be completed by April 2013 – and its Brand Match coupon at till offer.

The retailer’s sponsorship of the Paralympic Games also raised its profile during the period.

The underlying profit rise is in stark contrast to the 12.4% fall in first-half trading profits reported by arch-rival Tesco last month. Morrisons last week reported a 2.1% decline in like-for-like sales while Asda is due to report on third-quarter performance tomorrow.

Sainsbury’s said online sales grew at over 20% and it opened 49 convenience stores during the period as well as five supermarkets and three extensions.

Speculation had been mounting that chief executive Justin King may step down to take up a role within Formula One motor racing. However, the company made no reference to this. King will have been at the grocer for nine years in March.

King said: “Our share of the grocery market is the highest for almost a decade at 16.7%, with 31 consecutive quarters of like-for-like sales growth. We continue to succeed by remaining focused on delivering quality products, best-in-class service and value for our customers, without compromise. Brand Match, Nectar and our highly targeted coupon-at-till all reinforce our price competiveness.

“Whilst the wider economic situation remains challenging, we are well positioned to help our customers Live Well For Less. Our long-standing consistent strategy, combined with our customer insight and strong value-driven culture, will continue to deliver for customers, colleagues and shareholders.”