British supermarket group Sainsbury's has beaten expectations for first-quarter sales though growth did slow sharply reflecting a tough comparison with last year when shoppers stocked-up for a first Covid-19 lockdown.

The group said like-for-like sales, excluding fuel, rose 1.6% in the 16 weeks to June 26, its fiscal first quarter.

This compared to analysts' average forecast of a fall of 1.7% and a rise of 11.3% in the previous quarter.

Sainsbury's said sales of grocery, general merchandise and clothing were all higher than its expectations throughout the quarter. It said it outperformed competitors and grew market share.

It said it had further tough comparables ahead as pandemic restrictions continue to ease and customer behaviour normalises.

Sainsbury's said it expected to report underlying profit before tax of at least £660m in the 2021-22 year, up from £356m in 2020-21.

Meanwhile, the boss of Sainsbury's refused to be drawn on whether the supermarket group could become part of the fevered takeover activity gripping the sector, saying his focus was on delivering the strategy.

"I'm not going to speculate on where things are in the wider sector," CEO Simon Roberts told reporters in reference to three suitors pursuing rival Morrisons.

"We're very focused on our plan. We laid out a (strategic) plan in November to really deliver improvements for our customers and improve the value that we can create for our shareholders," he said after Sainsbury's updated on first quarter trading.

"We're only seven months into that (plan) but I hope you can see in the results that we've announced today some good early momentum," he added.

Shares in Sainsbury's are up 23% so far this year, buoyed by bid speculation after Czech billionaire Daniel Kretinsky raised his stake to just under 10% and Morrisons agreed a takeover bid.

Asked directly if Sainsbury's board had received any approaches, Roberts said: "If we had anything to update on, we'd be updating on it, so we've nothing to update you on."