ANY improvement in the situation of the under-pressure consumer is unlikely to prompt a change in behaviour, Justin King, chief executive of J Saisnbury has cautioned, after the UK's number three supermarket chain defied the conditions to record its 34th consecutive quarter of underlying sales growth.

Underlying sales at Sainsbury grew 0.8% in the 12 weeks to June 8, the first quarter of its financial year.

This compares to a 1% fall at market leader Tesco, a 1.8% decline at number four grocer Wm Morrison, and a 1.3% rise at Asda, albeit over different trading periods.

Mr King said: "It is good news if consumers are being more optimistic about the future. But we do not expect that to lead to a change in consumer behaviour."

Mr King's comments come after a prediction from Ernst & Young's ITEM Club this week that a recovery in consumer spending, thanks to tax changes and possibly a strengthening in wage growth, could boost the economy in the coming years.

This follows a period during which disposable incomes have been squeezed between static pay and rising prices for essentials such as fuel.

Sainsbury's has benefited from rising demand for its standard own-brand line By Sainsbury's, whose sales were up 7% year-on-year, and its top-end Taste the Difference range, up 10% to more than £1 billion.

Among its successes was the re-launch of Sainsbury's Little Ones nappies as the Huggies brand quit the UK.

Sales of branded groceries and its Basics line were flat, the supermarket reported.

Sainsbury's has continued to pick up market share, growing to 16.8% behind Tesco and Asda, although it remains number four in Scotland.

Sainsbury's online grocery sales rose 16% year-on-year, while convenience store sales increased 20% as shoppers restricted their weekly shop to avoid waste and topped up during the week.

More than half of its 70-strong store estate in Scotland are convenience outlets after nine openings north of the Border last year.

Mr King said he expected grocery sales in volume terms to continue to fall as shoppers sought to minimise waste.

He added that habits developed over the past five years, such as re-using leftovers, were unlikely to disappear.

Phil Dorrell, director of consultancy Retail Remedy, said: "Sainsbury's continues to outperform with metronomic regularity.

"Thirty-four quarters of continued growth – in the face of declining household spending – is a just reward for a firm that consistently gets it right."

But others warned that Sainsbury's was reliant on opening new stores and online sales.

"The performance is below par in terms of bricks and mortar core food sales," said Panmure Gordon analyst Philip Dorgan.

Sainsbury's total first quarter sales rose 3.3%, excluding fuel.

Its shares closed up 2.4p or 0.7% at 365.1p.

Sainsbury's strong performance prompted a call for increased wages by trade union Unite. Rhys McCarthy, national officer for food and drink at Unite, said: "There is something very distasteful about profits made by a business selling superior food products while its workforce's wages are low enough for them to qualify for food bank support."