Like-for-like sales growth at supermarket chain Sainsbury's slowed during the first quarter as the company faced up to what it called "the challenging economic environment".

However, non-food items continued to outpace the UK retailer's overall growth as expanded ranges were introduced into new retail space, while online sales were up 40%.

Sainsbury's said total sales were up 8.1% in the 12 weeks to 14 June, or 4.5% excluding fuel revenues.

That equated to a 7.3% rise in like-for-like sales, or 3.4% excluding fuel - down from 4.1% in the previous three-month period.

Chief executive Justin King said the "good" performance was in line with company expectations, but admitted that the global sales increases were in part driven by fuel price inflation.

He hailed the improved performance of Sainsbury's non-food merchandise in particular, also pointing to the surge in online sales.

"The challenging economic environment continued throughout the quarter," said King. "However, we are now serving nearly 18m customers a week and have delivered sales growth in line with our expectations.

"Whilst we anticipate that the environment will remain challenging, we operate from a strong financial position and our expectations for the full year remain unchanged."