The health secretary has acknowledged a global shortage of lateral flow and PCR tests is currently impacting the UK, after health leaders voiced concerns over low and "inconsistent" supplies.
Sajid Javid set out the situation in a phone call with Tory MP Sir Roger Gale who was inquiring on behalf of his constituents struggling to get tested.
The North Thanet MP said: "The long and the short of it is he says there is a worldwide shortage of lateral flow tests.
"A British company that is making them has ramped up its production line fourfold and we are buying the lot, plus anything we can get from anywhere else around the world, but we are competing in a global market."
Earlier in the day pharmacy bosses had warned getting hold of lateral flow tests was becoming a "huge" problem, with people requesting them every five minutes over the Christmas period.
Labour has urged the government to fix the situation, describing it as a "shambles".
Coronavirus: What you need to know
Has demand for lateral flow tests gone up?
In short, yes. The government has urged the country to regularly take lateral flow tests - repeating their advice particularly in the run up to Christmas and New Year celebrations.
Official guidance suggests individuals take a test on days when mixing with others indoors, and tells people to swab daily if they've been in contact with someone who has the virus.
The change in isolation rules in England (reducing quarantine time from 10 days to seven for people with Covid) also relies on getting two negative lateral flow results on days six and seven.
There are concerns without access to lateral flow tests key workers, including those in the NHS, will be unable to return to work after seven days of isolation.
Are there enough lateral flow tests to meet demand?The UK Health Security Agency (UKHSA) said nearly 900,000 test kits are being provided per day - double the supply seen before December 18.
As pressure mounted on Wednesday, official word from the government finally came via Tory MP Sir Roger Gale who relayed that the health secretary had confirmed a global shortage was impacting supply to the UK.
Sir Roger told the PA news agency: "Saj was very honest with me, he said, ‘look, there isn’t a quick fix’."
It confirms what Leyla Hannbeck, boss of the Association of Independent Multiple Pharmacies, had warned on Wednesday morning - describing supply as "patchy" and not enough to meet demand.
She told the BBC's Today programme: "Some days you get one box delivered and other days none. It isn’t enough for the pharmacies to deliver to the patients.
"Pharmacies are reporting that every five minutes approximately somebody comes in to the pharmacy asking for a test."
"Because of the issues around supply being patchy and inconsistent, it means that those who come for the test don’t always get it, which is very stressful not just for the pharmacy team but for the patient," Ms Hannbeck said.
"The scale of the problem is huge because the demand is high, because of the current guidelines."
The other option, ordering tests to your home online, has also encountered problems.
In a repeat of events in the weeks before Christmas, the government website on Wednesday was reporting there are no lateral flow tests available to order online.
It also said there are no PCR tests available for people - including key workers in England and Northern Ireland. People in Wales can still order the tests online for now.
There are also "very few available" in Scotland. In a Covid update on Wednesday, First Minister Nicola Sturgeon announced testing in Scotland will be prioritised for essential workers as supply and processing capacity is "under pressure".
"The current surge in cases means testing capacity – sampling and processing – is under pressure," she said.
"So we are now prioritising some slots for essential workers – such as NHS and transport staff – as well as for those who are clinically vulnerable or eligible for new Covid treatments.
"This ensures that essential workers get the test results they need to qualify for an exemption promptly."
'Everybody's been told to take a lateral flow test and yet you can't get hold of a test'
Labour has branded the situation "a shambles".
Shadow work and pensions secretary, Jonathan Ashworth, told ITV News: "Everybody's been told to take a lateral flow test and yet you can't get hold of a test in the chemist or when you try and order them online."
He added: "What is the health secretary doing? He really needs to get a grip of it.
"It's not clear from the government as to why there are these problems in the supply of the test, they've not given us any explanation."
Mr Ashworth called on ministers to explain why there's an apparent shortage of tests and outline "what they're doing to fix it".
The MP said there were NHS staff unable "to get back to the frontline" because they "can't get hold of tests".
Shadow health secretary Wes Streeting described said the dearth of supplies had been caused by "the Conservative government’s incompetence".
Work and Pensions minister Chloe Smith advised people who cannot get Covid tests through the government website to "try back again later".
Asked on BBC Radio 4’s World at One programme about test shortages, she said: "Now behind the scenes, obviously, we’ve got to make sure that the Gov.uk website and the way that people are accessing that is always there for people and able to get those kits to people.
"That is happening behind the scenes. I appreciate that every so often the site may go down but try back again later, because that is how we are making sure it is all there."
"But across all those methods, the government is working extremely hard to make sure that capacity is there."
Speaking on Wednesday from a vaccine centre the prime minister urged people to celebrate New Year in a "cautious and sensible way" and to take lateral flow tests.
"Take a test, ventilation, think about others – but above all, get a booster," Boris Johnson said.