A British trial will investigate U.S. drugmaker Pfizer's oral COVID-19 pill as a potential treatment for patients hospitalised with the illness, scientists said on Monday, as global coronavirus cases are surging once again.

The world's largest randomised study of potential medicines for COVID-19, dubbed the RECOVERY trial, will assess Paxlovid across hospitals in Britain. It has already been approved in the country for the early-stage treatment of coronavirus infections.

"Paxlovid is a promising oral antiviral drug but we don't know if it can improve survival of patients with severe COVID-19," said Peter Horby, a professor at the University of Oxford and joint chief investigator of the RECOVERY trial.

Scientists said they aim to mainly find whether Paxlovid reduces the risk of death among patients admitted to hospitals with COVID-19.

The study, led by the University of Oxford, will also probe whether the treatment shortens the length of hospital stay or reduces the need for a mechanical ventilator, they added.

The Pfizer treatment is part of a class of drugs called protease inhibitors, currently used to treat HIV, hepatitis C and other viruses, and works by stopping the virus from replicating.

(Reporting by Shanima A in Bengaluru; Editing by Amy Caren Daniel)