Home COVID testing kits have run out on the government’s website, a message on gov.uk says.
The message says: “Sorry, there are no more home tests available right now.
“Try again later.
“Or, you can go back and try to book a test site appointment instead.”
It comes less than 24 hours after an announcement that daily testing would become mandatory for anyone double-jabbed who comes into contact with a COVID-19 case.
From tomorrow, those fully vaccinated should take a daily lateral flow test for seven days to slow the spread of the virus, the government said.
People will be contacted by NHS Test and Trace or via the NHS COVID-19 app to tell them they are a contact of someone who tested positive and what action they need to take.
The move comes following a significant rise in Omicron infections in the UK with the variant expected to become the dominant strain in the UK by mid-December.
The shortage of lateral flow tests could also become a bigger problem from Wednesday when, if MPs vote in favour of the new coronavirus rules, the NHS COVID pass will be made mandatory for nightclubs and venues with large crowds.
It would mean those who haven’t been vaccinated cannot easily provide a negative home test as an alternative way to gain entry.
It is unclear why there is a shortage of home testing kits.
Those who need a lateral flow test can also try to pick up a kit from local pharmacies and they are also offered by some schools and workplaces.
Another option is to book a test site appointment instead.
There appeared to be no problems with the availability of PCR home test kits.
Earlier on Monday, Health Secretary Sajid Javid advised that people should take lateral flow tests before meeting loved ones over the festive period because of the Omicron variant.
Mr Javid told Sky News that the UK is “once again in a race between the vaccine and the virus” as he urged everyone eligible to take up the offer of a booster jab.
The health secretary said the plan is for jab centres to be open for at least 12 hours on every day of the Christmas holidays, apart from Christmas Day itself.
“We have got to act early,” Mr Javid added, telling Sky News that ministers are “throwing everything” at the booster rollout, which is “more important than ever”.
Mr Javid later told Kay Burley that there are currently 10 people in hospital with Omicron.
“At this point in time, I cannot confirm a death,” he added.
Meanwhile, the NHS acknowledged the issues people have had trying to book in a booster vaccine on Monday after individuals had complained of receiving error messages, being stuck in queues for hours, or facing website glitches.
In a tweet, the NHS said there is “extremely high demand” and people should try again later today or tomorrow.
On Sunday, the UK reported 1,239 additional confirmed cases of the Omicron variant – the highest daily rise and nearly double the previous high recorded on Saturday.
The total number of cases of the variant now stands at 3,137 in the UK.