One of the biggest private Covid-19 testing sites in the UK is set to open on Wednesday with customers able to get their results within 24 hours.

French firm Biogroup will open two pop-up sites in Marylebone and Notting Hill in London and a megalab able to run 15,000 tests a day or 100,000 every week.

Bosses say they want to help staff return to offices safely and reassure travellers heading to families ahead of the Christmas break, when rules will be relaxed.

The company believes it can eventually offer a 20-minute turnaround service by the new year, with the testing potentially rolled out to airports and travel hubs.

Biogroup is already working with Air France in Paris.

The RT-PCR (RealTime Reverse Transcription Polymerase Chain Reaction) test service, which costs £135, will see professionals take nasal and throat swabs and is 99.9% effective at identifying Covid-19, the company added, due to offering a so-called “end-to-end” service.

Businesses have been desperately looking for ways to get staff back to offices without facing accusations of not putting their safety first and Biogroup hopes to sell the service to major corporate institutions.

Some companies are also asking staff to be tested following any periods of self-isolation, despite NHS guidelines saying NHS testing services should only be accessed if a patient is showing symptoms.

There has been a boom in private testing available, including at Boots the Chemist and at other private medical businesses.

The Government is looking at ways for commercial testing to be accredited solely through the UK’s National Accreditation Body (UKAS), to make accreditation of private Covid-19 tests faster and more efficient.

Launched in France, Biogroup already has around 700 labs in the country and contracts with the French government.

Dr Astrid Gouillard, chairman of Biogroup UK, said: “Testing is central in the fight to control the spread of the virus. It allows those infected to be isolated to prevent or at least slow down the number of new infections.

“It is also key in the future management of the pandemic, establishing how much the virus has spread across the broader population and understanding the level of immunity across the UK.”

“The additional capacity from private labs for both corporates and consumers will considerably help people return to normalcy by reducing self-isolation and re-opening the country to business travel.”

The tests used are different to those used in a trial in Liverpool, which were recently shown to be less effective at avoiding false negatives.

Rapid coronavirus tests rolled out in the city missed more than half of those who had Covid-19, preliminary data suggested.