Health officials must abandon strict production rules that are hampering the introduction of mass testing for coronavirus, scientists warned on Wednesday, after the government admitted that just 2,000 of half a million frontline NHS staff have been tested to date.

Procedures drawn up by Public Health England describe the precise chemicals and equipment that must be used to test patients. But with specific reagents in short supply, senior researchers told the Guardian that the UK must find alternatives to avoid more delays, with one arguing: “These are not normal times.”

Their plea came as the prime minister was forced to address mounting anger about the government’s failure to increase testing, just weeks after it had appeared to rule out such a strategy. Ministers have been consistently flummoxed by questions on the issue.

In a video message posted on Twitter on Wednesday evening, Boris Johnson said the country need to “massively ramp up” the two separate tests that show whether people have, or have had, the disease.

“It’s crucial people who do have the disease are able to be tested positive and to take the necessary steps to isolate at home in the way that I am doing and many, many others are doing,” he said.

The UK’s poor testing figures compared with other nations have caused a huge political backlash, with critics asking why the government is both failing to source the right equipment and refusing to agree to expand testing to the general population.

Only around 8,000 hospital patients and NHS staff are being tested daily – well short of the government’s targets and far below the 70,000 a day achieved in Germany. In total, just 2,000 NHS workers – or 0.4% of those being exposed to the virus – have been tested so far, meaning thousands in isolation cannot get back to work.

Ministers have struggled for four days in a row at No 10’s daily press conference to explain why testing is so slow. In an attempt to solve another logistical barrier, NHS England also directed all trusts to lift the 15% cap on staff testing and use all their spare testing capacity to help solve the problem.

But Prof Nicola Stonehouse, a molecular virologist at Leeds University, said that efforts to scale up testing were being frustrated by over-reliance on specified reagents, enzymes and other chemicals. “It is holding things up,” she said. “If we could get over this, we could get the testing centres up and running so much faster, and that’s got to be a good thing.

“The NHS have very specific requirements and there is good reason for that. It makes sure that standards are maintained. But there are alternatives. They need to be optimised and validated, but you can fast-track that if you have enough people. It wouldn’t take a lot of time.”

The health secretary, Matt Hancock, announced last week that the government had bought 3.5m antibody tests. But the Guardian understands the UK has actually put in orders for up to 40m.

Facebook Twitter Pinterest Coronavirus testing site in a car park at Chessington World of Adventures in Greater London. Photograph: Yui Mok/PA

Dr Catharina Boehme, chief executive of the non-profit Geneva-based Foundation for Innovative New Diagnostics, a WHO collaboration centre, told the Guardian presidents and prime ministers were trying to outbid each other to secure testing kits. “In all countries we have prime ministers calling the CEOs and diagnostic companies to try to get hold of the stocks,” she said.

“Indonesia and Peru we know have offered to order several million tests and send private planes to pick the tests up. There is more going on behind the scenes to secure supplies.”

Universities have received a flurry of urgent calls from the government to assist in scaling up virus testing. Weeks ago, certain enzymes were in short supply. More recently, requests came in for chemicals that release the virus’s genetic code, the first step in the process of detecting the virus in swab samples.

“The protocols say they want specific types of reagent for that, but there are lots of ways to do it, there are many reagents you can use,” Stonehouse said. “We can do this, and with appropriate controls, the risks are low and the benefits could be high.”

The stringent rules around test chemicals and equipment are designed to ensure that tests are reliable and consistent across the NHS. The health service benefits because it can order in bulk from a single supplier at a preferential rate. But the procedures are so prescriptive that all laboratories can end up using the same equipment, suppliers and chemicals, so when demand spikes, there are no other approved products to use.

“On a normal day, this works,” said Eleanor Riley, professor of immunology and infectious disease at the University of Edinburgh. “But these are not normal times. At the moment we need to ramp up testing.

“Research labs, which tend to operate in a much less regimented manner, have the skills, equipment and quite possibly sufficient reagents to contribute to this effort,” she went on. “They won’t be exactly the same items that Public Health England use, but they will work just as well. Research labs are also very used to working to validate their data across labs to ensure their data are comparable to that of their colleagues.”

The British In Vitro Diagnostics Association, BIVDA, said the problem was a shortage of reagent kits in the global supply chain. While manufacturers are producing the kits as rapidly as they can, the firms are having to prioritise what products are shipped where.

Stonehouse said chemicals were not the only hurdle that scientists faced in trying to help in the acceleration of testing. A large swath of university-trained researchers have volunteered to run testing equipment, but have been held up amid legal concerns about having them working at NHS and other testing facilities. “This seems to be stopping things going forwards,” Stonehouse said. “It’s an overreaction. We have staff in ITU who have not worked in intensive care before because we need them there. We need that flexibility on testing.”

Labour called on Wednesday for Boris Johnson to publish a clear “national testing strategy” that sets out exactly how the government plans to expand its programme in the coming weeks.

As well as coming under fire over the logistical problems, No 10 and its advisers are facing questions about why they are refusing to commit to a future strategy of mass testing of the general population as well as of NHS workers and patients in hospitals.

Public health experts have warned that mass testing for live cases of the virus is essential if the UK wants to ease the lockdown, arguing that it will be necessary to find any new hotspots and suppress them using aggressive quarantining and contact tracing methods.

Jonathan Ashworth, Labour’s shadow health secretary, told the Guardian: “The government claims to have abandoned its herd immunity strategy, but without clear testing, many are asking what our strategy actually is.”

Alok Sharma, the business secretary, was the latest minister to decline to confirm that moving to mass testing was part of the agenda as he appeared at the No 10 press conference on Wednesday, with Boris Johnson still in isolation.

Public Health England has repeatedly emphasised that wider testing to see who is immune is a greater priority, but this does not find people who are currently infectious.

Yvonne Doyle, medical director of Public Health England, said on Wednesday that the government wanted testing to go “from the tens of thousands to the hundreds of thousands”, although the intended split between tests for live cases of the virus and immunity is not clear.