The owner of Primark, Associated British Foods (ABF), has said sales at the discount fashion chain have been “lower than expected” in recent months due to lower footfall affected by rising coronavirus cases.

However, the group also upgraded its profit guidance for the past year as Primark benefited from lower store labour and operating costs in the latest quarter.

On Monday ABF told its investors that profits for the past financial year are set to overtake figures for the previous one, with strong performances by Primark and its grocery business contributing to that.

The consumer giant was also boosted by “much improved” profits at its sugar operation.

Primark is expected to reveal sales worth around £3.4 billion for the half-year to September after momentum was dented slightly in the summer, the company said.

In the third quarter the chain saw “very strong trading” with the reopening of its stores, but was affected by a change in consumer sentiment as more people were “pinged” on their NHS app and had to isolate.

In a statement, ABF said: “In the UK our sales were affected by the rapid and significant increase in late June and early July in the number of people required to self-isolate following contact tracing alerts – the ‘pingdemic’.

“Data shows that high street footfall was impacted by the caution displayed by many consumers at that time.

“The self-isolation rules were then eased in early August.

“Correspondingly, like-for-like sales showed a consistent improvement through the period from a decline of 24 per cent in the first four weeks of the quarter to a decline of 8 per cent in the last four weeks.”

In terms of a decline, the company expects to see a 17 per cent fall in the fourth quarter compared with the same period from 2019.

It is also currently experiencing “some delays” to the stock of its autumn/winter season inventory due to “port and container freight disruption”.

Covid-19 restrictions have also “held back” the company’s progress on developing its pipeline of new stores, with difficulties in assessing and evaluating new sites and negotiating with potential landlords, it said.

On a more positive note for ABF its grocery revenues are set to be ahead of last year, as it receives a boost from growth in its Twinings and Ovaltine drinks businesses.

It added that its AB World Foods, Silver Spoon and Westmill businesses saw sales significantly ahead of pre-pandemic levels and continued their sales bounces from last year.

However, sales reduced at its Allied Bakeries arm – which makes Kingsmill bread – after the end of a supply deal for the Co-op supermarket chain.