Sainsbury’s has posted a fall in first-quarter sales and named a new chief financial officer to replace Kevin O’Byrne.

Sainsbury’s sales excluding fuel slipped 4.5% in the period to June 25 and were down 4% like for like as general merchandise took a hit. The grocer retained its existing full-year profit guidance and said it was pleased by a “good grocery volume market share performance”.

Sainsbury’s also revealed it is promoting Bláthnaid Bergin, commercial and retail finance director, to succeed O’Byrne who has decided to retire in March next year after six years as CFO.

Sainsbury’s grocery sales fell 2.4% “against last year’s elevated Covid-19-driven levels” and were 8.7% ahead of pre-pandemic levels. Total general merchandise sales were down 11.2% in the quarter. Argos was down 10.5%, Sainsbury’s general merchandise down 14.6% and clothing down 10.1%.

Sainsbury’s chief executive Simon Roberts said: “We really understand how hard it is for millions of households right now and that’s why we are investing £500m and doing everything we can to keep our prices low, especially on the products customers buy most often.

“We’re working hard to reduce costs right across the business so that we can keep investing in these areas that customers care most about. The progress we are making on improving value, quality, innovation and service is reflected in our improved grocery volume market share.

“Our customers are watching every penny and every pound, but they also look to Sainsbury’s when they want to treat themselves, particularly at special occasions. We are really connected to our customers and through strong delivery of our plan, we have outperformed the market at key events such as the Jubilee.

“I would like to thank my colleagues for their brilliant efforts this quarter. We are proud to be the first major supermarket to pay the living wage to all colleagues, regardless of where they live – and to have increased Sainsbury’s colleague pay by 25% and Argos by 39% over the past five years. The pressure on household budgets will only intensify over the remainder of the year and I am very clear that doing the right thing for our customers and colleagues will remain at the very top of our agenda.”

As he prepares to hand over the finance reins, O’Byrne said: “It has been a real privilege to work with all my colleagues in Sainsbury’s. I am very pleased to be handing over to Bláthnaid who will bring great commercial drive to the role. I shall continue to focus, with my team, on delivering our plan and driving momentum while managing a smooth transition over the next nine months.”

Roberts said: “Kevin and I have worked closely since I joined the business in 2017. He has been a great business partner, making a strong contribution. On behalf of all of Sainsbury’s colleagues, I would like to thank him for all he has done.

“Bláthnaid is well embedded in our business and is a highly respected leader. I am also looking forward to continuing to work alongside her to deliver our strategy.”