In England it was not possible to book any walk-in PCR tests for a few hours on Monday due to the “high demand”, as places were not available in any region.
Some were available in Northern Ireland, Scotland and Wales before the situation eased later in the day.
Slots became available in each region over the course of the afternoon, with the UK health authority saying the restricted availability was “temporary”.
A UKHSA spokesman said: “Appointments for PCR testing are available, but high demand may result in temporarily limited availability in some areas. Additional dates are available for booking every afternoon.
“Tests play an essential role in keeping people safe and managing the spread of Covid-19. We are very grateful to all who follow government orders and get tested to protect themselves, their loved ones, and their communities.
“Anyone with symptoms or who is instructed to have a PCR test done should still come in to have a test delivered to their home or testing site.”
Paramedic Ethan, from Southampton, said he was “furious” about initial fears he might miss work after waking up with symptoms of Covid.
He told the PA news agency: “I have been experiencing symptoms of a new cough overnight and until this morning that meets Covid guidelines for requiring a PCR test.
“I tried to book an on-site test this morning for which nothing was available. I had to book a test kit with an estimated delivery time of two days and I am not sure how long it will take for the results to be returned.
“I’m an NHS paramedic and should be back to work tomorrow to work through the new year.
“My trust already has high sickness rates from stress and other ailments and Covid-19 related illnesses, and I fear that this delay in my results compared to the time it would take me to drive is due to PCR and the Results from this will have a negative impact on my colleagues and the public. “
Other Twitter users said the lack of availability could affect travel plans, sporting events, and business appointments.
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