Workers in the food supply chain will be exempt from Covid self-isolation rules as the government brings in a "test to return to work" policy amid concerns about empty supermarket shelves.
Environment Secretary George Eustice said 10,000 staff members, possibly more, would fall under the rule change.
It means those who have received an NHS Covid 19 app alert to isolate, or have been called by Test and Trace, will be able to continue working if they test negative.
Priority testing sites, including the largest supermarket distribution centres, have been earmarked for rollout this week - with up to 500 sites poised to partake in the initiative next week.
However, shop staff will not be included in the exemptions, despite supermarkets warning earlier this week that the rising number of retail workers being forced to self-isolate was starting to affect the availability of some products, as retail bosses urged shoppers not to stockpile goods.
When questioned why this was the case, Environment Secretary George Eustice said it was easier to manage staff shortages on a store level.
He told BBC Breakfast: “Well, the main reason is that would be a really significant undertaking, as you’re talking then thousands of different shops, and many more people, and we still want to maintain the test, trace and isolate system.
“We know that the most important thing is to ensure that those main arteries in our food supply chain keep working, that the lorries keep going from depots to get goods to store and that the food manufacturers can continue to manufacture the goods to get it to the depots.
“When you get to store level, of course, yes, there will be some difficulties, they will have staff shortages. But it is easier to manage at that level.”
It comes as the Co-op said it was "running low on some products", while Iceland said shops might have to shut. Echoing similar concerns, grocers have also said a shortage of HGV drivers and the hot weather were contributing to delivery glitches.
Helen Dickinson, chief executive of the British Retail Consortium, said shop supplies are holding up but swift government action was needed to avoid further empty shelves.
"I don’t think there is any need for members of the public to be stockpiling what they buy," she said.
"What we are seeing is pockets of issues in specific places where case numbers are particularly high and the most important thing is that the government acts now before the situation does get more serious."
At a meeting with supermarket leaders, the Department for Environment, Food and Rural Affairs (Defra) said the government committed to actions to support the resilience of the food supply chain.
'For key food manufacturers we're going to change the system'
Environment Secretary George Eustice told broadcasters: "We recognise there are some staff absences in the food supply chain.
"So for things like supermarket depots and key food manufacturers, we're going to change the system".
Mr Eustice said 10,000 staff, possibly more, could be impacted from the rule change.
Health Secretary Sajid Javid added: "As we manage this virus and do everything we can to break chains of transmission, daily contact testing of workers in this vital sector will help to minimise the disruption caused by rising cases in the coming weeks, while ensuring workers are not put at risk."
Defra, which said supermarket leaders downplayed fears of shortages, acknowledged that even people who are fully vaccinated may still become infected.
Earlier on Thursday, Business Secretary Kwasi Kwarteng said a "very narrow" list of sectors whose workers will be exempt from isolation rules would be published.