The UK government turned down an opportunity to buy tens of thousands of potentially “game-changing” coronavirus tests from an award-winning British scientist just days after Matt Hancock pledged to hit 100,000 tests a day by the end of April.

As the UK looks set to miss its target, the Guardian can reveal that the government spurned an offer nearly four weeks ago to purchase vast quantities of US-approved home testing kits from a firm carrying out tests for the US air force, and the states of Florida and Alaska.

The California-based company, Curative, offered to supply 50,000 saliva tests a week immediately, with the potential to increase this to 50,000 tests a day. On the day of the offer, 4 April, the UK had capacity to do just 15,499 tests a day and was only testing 8,651 people a day – far lower than other European nations such as Germany.

The missed opportunity comes as the UK remains under severe strain due to an apparent lack of its ability to pursue a ‘“test and trace” strategy. Experts have said the UK should not end the lockdown without developing a clear strategy for stamping out the virus through mass testing.

On Monday, the latest day for which figures are available, only 43,453 tests were carried out on 29,000 people, while the daily capacity of 73,400 remains well below the target of 100,000, which the government has pledged to hit by Thursday. The government can currently only provide 5,000 home-testing kits a day, but said it is “ramping up” this capacity.

The Curative test, which has been approved by the US Food and Drugs Agency (FDA), is less invasive and easier to use than the nasal swabs currently favoured in the UK as they only require a saliva sample from inside the mouth, rather than deep in the back of the throat or nose.

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The two-minute test is self-administered and can be used at home without supervision, removing the need for potential Covid-19 victims to drive to testing facilities. It also lifts some of the strain on NHS staff, who are required to wear full personal protective equipment (PPE) to oversee the current tests. The results are analysed in the US and emailed within 72 hours, Curative said.

Early studies in the US, including one by Yale University, have found the saliva test to be as accurate - if not more so - than the nasal swab test and some scientists have hailed it as “game-changing”.

Curative is rapidly expanding its testing in the US and currently provides tests for the US air force as well as the states of Florida and Alaska, and the city of Los Angeles. It says it conducts nearly a quarter of all testing in California.

Philip Beales, a professor at the University College London Institute of Child Health, who has been helping to coordinate the efforts of UK testing firms, said saliva tests such as those provided by Curative “really could get us out of this epidemiological nightmare”.

In the US, experts have predicted that saliva testing will allow three times as many people to be tested per day and reduce the need for PPE by as much as 90%. Officials in Oklahoma and New Jersey are planning to deploy saliva tests in the coming days, the Washington Post has reported.

The so-called “next-gen” saliva test was developed in just 10 days earlier this year by Curative, which is run by 25-year-old Fred Turner, who won the EU’s contest for young scientists in 2013.

The Yorkshire-born scientist was named UK young engineer of the year in the same year when, aged 17, he built a DNA machine from his bedroom to discover whether he had the “ginger gene”, after merciless teasing from his schoolmates about why his brother had red hair and he had brown hair. He turned his focus to the coronavirus when the pandemic took hold in January.

Turner’s company contacted the UK government to offer its tests on 4 April, two days after Hancock’s 100,000-tests-a-day pledge. It received a brief reply from an unnamed official three days later to say the government was not interested because Curative’s test was “undifferentiated against the existing portfolio of tests”.

However, the response has caused confusion because the UK is not thought to have any of the next-gen saliva tests, as officials have focused on the nasopharyngeal swabs.

When contacted by the Guardian, the Department of Health and Social Care said it already had partnerships to supply hundreds of thousands of [nasal] swab tests and did not need any more.

Labour’s Bill Esterson, the shadow international trade minister, said: “The government could have hit its 100,000 target weeks ago. Curative gave the government the scientific evidence needed to show they met the specification on 4 April. It makes no sense that the government dismissed them out of hand.”