New delivery arrangements have been agreed for rapid coronavirus tests after orders on the Government website were temporarily suspended amid high demand.
Health Secretary Sajid Javid insisted there is no shortage of such tests and said the issue is with delivery.
He told MPs in Parliament that he has agreed new arrangements with Amazon and others to address the problem.
The UK Health Security Agency (UKHSA) said the pause is temporary and availability refreshed daily, with people encouraged to revisit the website from Tuesday.
Mr Javid told the Commons: “I can reassure this House that the UK has sufficient lateral flow tests to see us through the coming weeks.
“If anyone finds they are unable to get a kit online, they should check the website the following day or pop down to their local pharmacy and pick up a kit.”
He said limits on ordering tests are linked to delivery capacity and told of new arrangements to tackle the issues.
Mr Javid said there is “no shortage of actual tests”, adding that there are “tens of millions” available.
He said the “the limiting factor” is the ability to deliver the tests, branding the current arrangements with Royal Mail alone as “not enough”.
He added: “There are new arrangements that I’ve reached with Amazon and other delivery methods.”
He said a record number of tests would be delivered each day, and the number of “access points” is being increased, including more through pharmacies.
Earlier, Boris Johnson was asked about potential supply issues during a visit to a vaccination clinic near Paddington in west London, and told broadcasters there is a “ready supply”.
“Due to exceptionally high demand, ordering lateral flow tests on gov.uk has been temporarily suspended to fulfil existing orders.”
Mr Johnson said the demand seen shows “that people are doing the sensible thing, and getting tests”.
The daily testing approach replaces the requirement for double-jabbed people identified as a contact of someone with Omicron to isolate.
New regulations are also set to be put to a debate and vote in the Commons this week on the NHS Covid Pass becoming mandatory for entry into clubs and other large gatherings – but with a negative home test as an alternative for the unvaccinated.
Labour deputy leader, Angela Rayner, accused the Government of being “reckless” over its “inability to procure properly and plan for civil contingencies”.
She tweeted: “Boris Johnson has his priorities in the wrong place.”
Paul Taylor, a 37-year-old pharmacy technician from Leeds, told the PA news agency he was “frightened” at the prospect of being unable to order any lateral flow tests.
“(I have) only recently started to socialise normally (going to the gym, attending big events). Doing regular LFTs has relieved the anxiety of potentially passing anything on that I’ve felt throughout the pandemic.”
“I’m frightened because without tests I only have two choices: go out but risk passing on the virus to other people or stay in and return to self-imposed lockdown.”
Jessica Keogh, a 32-year-old executive assistant from London, told PA she had run out of lateral flow tests and was unable to order more.
“It’s actually my worry that I won’t be able to get any before Christmas and I will worry about being able to visit my family,” she said.
There did not appear to be any problems with the availability of PCR home test kits.