All travellers returning to the UK must take a PCR test and self-isolate until they receive a negative result.
Anybody who is a contact of suspected Omicron cases must self-isolate, regardless of their age or vaccination status.
Meanwhile, face masks are once again compulsory in certain settings in England including supermarkets and public transport.
Health Secretary Sajid Javid said he hopes the tougher rules will be “temporary” as scientists work to find out more about the new variant.
However, despite customers being expected to wear face masks in supermarkets, different retailers are taking different approaches to enforcing the new rule.
Confirmed Omicron variant Covid cases in the UK
Association of Convenience Stores chief executive James Lowman said: “We are helping retailers to prepare for the change in face covering rules, but they are extremely concerned about abuse against their staff from customers who don’t want to wear a face covering in a shop.
“We will continue to urge stores to communicate the rules, but not to challenge those who refuse to abide by the rules.”
Here is what each supermarket has said about face masks so far.
Iceland face mask rules
Iceland has said it will not force shoppers to wear face masks amid concerns over the treatment of staff.
Managing director of Iceland, Richard Walker, told the Daily Mail: “We fully support the reintroduction of compulsory face masks in shops, however, we won’t be asking our store colleagues to police it.
“Our store teams, alongside all retail workers, have shown heroic efforts in terms of ensuring safety for customers and building back consumer confidence and it’s crucial that we stay focused on the long-term recovery of the high street.
“We need to continue to encourage people to shop in stores if they feel comfortable, and I’m hopeful that the latest guidelines won’t discourage customers from doing so.”
Aldi face mask rules
Meanwhile Aldi have taken the opposite approach and asked all customers to wear a face mask when visiting UK stores.
Masks remain compulsory in Scottish and Welsh stores while new measures will be introduced in England.
Aldi UK chief executive Giles Hurley said: “The safety of our colleagues and customers is our number one priority.
“Following the latest government announcement, wearing a face covering will be mandatory for everyone that shops at Aldi from Tuesday November 30, except for those who have a medical exemption.”
Asda and Morrisons face mask rules
Asda and Morrisons will update guidance on face mask rules on Monday, according to reports.
Both supermarkets currently offer free face masks to customers in-store.
Lidl face mask rules
Lidl said: “As of the 30th of November 2021 wearing a face covering in our stores is mandatory in line with government regulations, to help keep everyone safe.
“A member of security may remind customers of the requirement to wear a face covering in our stores. However, we understand that some customers are exempt from doing so*.
“A gentle reminder, when purchasing age-restricted products, you may be asked to temporarily remove your face covering by store colleagues to verify your age.”
Tesco face mask rules
Tesco has said it will be “continuing to follow government guidance” as new Covid measures a reintroduced in England.
As a result, Britain’s largest grocer is asking its customers to “keep wearing a face covering”.
A message on the supermarket’s website reads: “Please keep wearing a face covering in our stores if you can.
“The government expects and recommends that people continue to wear a face covering in crowded and enclosed spaces.
“So we’re encouraging our colleagues and you, our customers, to continue wearing face coverings if you can.”
Sainsbury’s face mask rules
Sainsbury’s will also be asking customers to wear face masks.
A message on its website reads: “From Tuesday 30th November 2021, we are following government regulations and ask you to wear a face covering whilst in our stores, however, we completely understand if you have an exemption or reasonable excuse under the applicable regulations.”