Downing Street has issued a statement on face masks following the Prime Minister's announcement rules will be 'tightened up' in shops and on public transport.
New measures on people coming into the country isolating have also been announced to help combat the spread of the Omicron Covid-19 variant.
At a press conference this evening, Prime Minister Boris Johnson said people will 'have to' face coverings in retail settings or on public transport, but said Health Secretary Sajid Javid would give more detail 'in the course of the next day or so'.
READ MORE: Omicron: Everything we know as new coronavirus variant detected in the UK
Downing Street later confirmed the move will come into force next week.
The statement, which was issued following the press conference, read: "Face coverings will be made compulsory in shops and on public transport from next week.
"All hospitality settings will be exempt."
Greater Manchester mayor Andy Burnham said: "This is right but shows why they shouldn’t have been relaxed. It will now be harder, and take longer, to get levels of compliance up to where we need them to be."
The PM also said anyone entering the UK will be required to take a PCR test by the end of the second day of their arrival - and must self-isolate until they have a negative result.
In addition, all contacts of those who test positive with a suspected case of the Omicron Covid-19 variant must self-isolate for 10 days, regardless of their vaccination status.
It comes after the first cases of the Omicron variant were identified in the UK.
The Prime Minister warned that the new variant, seen for the first time on Tuesday in southern Africa, spreads 'very rapidly', and could be more resistant to vaccinations - even spreading between two double vaccinated people.
Earlier, Health Secretary Sajid Javid announced that from 4am on Sunday 28 November, non-UK and Irish residents who have been in Malawi, Mozambique, Zambia and Angola in the previous 10 days will be refused entry into England.
They join the six countries added to the list on Thursday night - South Africa, Botswana, Lesostho, Eswatini, Zimbabwe and Namibia.
The UK Health Security Agency (UKHSA) confirmed today that two cases of COVID-19 with mutations consistent with variant B.1.1.529 - known as the Omicron variant - have been identified in the UK.
The Government said patients that have tested positive and all members of their households are being re-tested and told to self-isolate while further testing and contact tracing is underway.
Sajid Javid revealed that individuals and their households are self-isolating after one case was found in Brentwood, Essex, and a second one in Nottingham.
It was originally reported that case was found in Chelmsford, however this has since been corrected by Essex County Council.
UKHSA is carrying out targeted testing at locations where the positive cases were likely to have been infectious.
Addressing the nation from Number 10, the PM said: "The measures that we're taking today, including on our borders and on face masks, are temporary and precautionary.
"We will review them in three weeks. At that point, we should have much greater information about the continuing effectiveness of our vaccines.
"I very much we will find that we continue to be in a strong position and we can lift these measures again, but right now this is the responsible course of action to slow down the seeding and the spread of this new variant and to maximise our defences so that we protect the gains we've worked for so hard and so that we can continue to save lives."
