The approval follows promising results from a late-stage study of the drug, and comes in the middle of a massive wave of COVID-19 cases in India, which has overwhelmed its health system and left many hospitals short of critical oxygen supplies.

Cadila said patients given its therapy in clinical trials had shown lesser need for supplemental oxygen, which is given to seriously ill COVID-19 patients to increase its supply in the blood and lungs.

About 91% of patients treated with the drug, branded Virafin, tested negative for COVID-19 in standard RT-PCR tests by day seven, compared to nearly 79% who were given the standard of care, the company said earlier this month.

"The fact that we are able to offer a therapy which significantly reduces viral load when given early on can help in better disease management," Cadila Managing Director Sharvil Patel said. "It comes at a much-needed time for patients."

India reported the world's highest daily tally of coronavirus infections for a second day on Friday, surpassing 330,000 new cases.

Cadila's drug, known as Pegylated Interferon alpha-2b, was originally approved for liver disease Hepatitis C and launched in India 10 years ago. It is being repurposed to treat COVID-19.

The company's shares reversed course following the news, and were last up 3.2% at 570 rupees in afternoon trading on the National Stock Exchange.

(Reporting by Sachin Ravikumar in Bengaluru; Editing by Shounak Dasgupta)