Pub giant Greene King has been forced to shut 33 pubs in the past week while retail and leisure bosses have also faced closures after staff were told to isolate by the NHS Covid app.

Nick Mackenzie, chief executive of Greene King, said he believes current self-isolation rules need reformed after he was forced to shut some pubs or reduce opening hours.

Latest figures showed more than 500,000 people in England and Wales were notified by the NHS app to self-isolate in the week up to July 1.

People who have come into contact with someone who has tested positive for the virus must self-isolate for 10 days.

Mr Mackenzie told BBC Radio 4’s Today programme: “This is a problem and I think it could get worse. It is disruptive to the business.

“We had to close, in the last seven days, 33 pubs due to lack of staff because of self-isolation.

“Across the industry we think it is about one in five of our team members who have been affected by this and therefore it is causing a real issue for us setting up business on a daily basis – we’re having to have shortened hours in some circumstances.”

Mr Mackenzie, whose group runs 2,500 pubs, hotels and restaurants across the UK, called on the Government to expand its test and release scheme to allow staff who test negative for coronavirus to return to work after being “pinged”.

Fellow pub owner Young’s also reported last week that around 350 of its staff were isolating due to Covid tracing rules.

Trade group UKHospitality warned MPs last week that about “a fifth” of workers in the sector were self-isolating as a result of “being pinged”.

Chief executive Kate Nicholls added that changes due in August to allow double-vaccinated workers to avoid isolation will have limited benefit until September due to the younger demographic of hospitality staff.

Helen Dickinson, chief executive of the British Retail Consortium, said the rising number of self-isolations is also having a “significant impact” on retail stores.

“Community cases continue to rise fast in many areas of the UK, creating a challenge for many shops and distribution centres,” she said.

“Given the success of the vaccination programme in reducing the number of serious cases, the Government should bring forward the August 16 date, allowing retail workers who show a negative PCR test to avoid self-isolation, as they have done for some NHS workers.”

Meanwhile, Richard Walker, managing director of the supermarket group Iceland, said around four per cent of the total workforce were currently absent because of coronavirus.

“We have got over 1,000 people absent due to Covid, that’s the highest ever since testing began,” he told the BBC.

“It’s about 4% of our total workforce of 30,000. In fact, we have just announced employing an additional 2,000 people on top of that to give us a deeper pool of labour, because so many people are now getting pinged.”

If it continues at this current trajectory with the same policies still in place, this represents another significant bump in the road that could bring our sector’s rebuilding process to a halt

Asked about the impact on the business, he said: “A number of stores have had to close and the concern is that as this thing rises exponentially, as we have just been hearing, it could get a lot worse, a lot quicker.”

Health club group Anytime Fitness said it believes closures across its more than 175 clubs will be “inevitable” due to the current system.

Neil Randall, chief executive of the company, said: “We’re at a time where our industry is clambering back to its feet and looking to rebuild cash reserves that were decimated by the pandemic and as restrictions drop, case rates and the amount of ‘pings’ being sent out will likely continue to rise.

“If it continues at this current trajectory with the same policies still in place, this represents another significant bump in the road that could bring our sector’s rebuilding process to a halt.”

Humphrey Cobbold, chief executive of rival PureGym, said: “We’ve been talking for a while internally about living in the ‘United Pingdom’ and it has become a huge challenge for individuals and businesses.

“Up to 25%, in some areas, of our staff have been asked to self-isolate – we’ve been able, through flexibility and sharing of labour, to keep sites open so far but it has been a very close call in certain circumstances.”