The firm saw turnover rise from £218.4 million to £619.2 million in the year to June 2021, when it processed 25 million PCR tests. The Times said the brand had previously made a loss.

The Northern Ireland-based brand told The Times it had reinvested profits and that the UK government “could not have got through the winter of 2020 without what we were doing”.

As well as its government contracts, Randox set up many Covid test centres at airports as well as in towns and cities, offering traveller tests.

A spokesperson for Randox told TTG: "As the largest diagnostic company from the UK, with over 40 years of innovative experience and with £350m of prior investment in biochip diagnostic technology, Randox was uniquely situated to respond to the national need when COVID-19 emerged in early 2020.

"These accounts show a turnover of £620m, with profit after tax of £224m. All profits are taxed in the UK and no dividends have been taken. During the reporting period, £141m was reinvested in laboratory and supporting infrastructure and £50m of Corporation Tax was payable.

"Randox can also confirm that, while £776.9m of DHSC contracts were awarded to Randox during the pandemic, payments from DHSC to March 2022 have amounted to £419m."