India reported a new variant of the coronavirus on Wednesday as it struggled with the highest single-day tally of new infections and deaths this year.

The variant, described by officials as a "double mutant," has been found in more than 200 samples in the hardest-hit western state of Maharashtra, which is home to India's financial capital of Mumbai.

Health officials said the new variant had not been detected in large enough numbers to link it to the surge in cases in Maharashtra and other states including Kerala and Punjab.

Epidemiologists said the term "double mutant" refers to an entirely new variant that has the characteristics of two already identified variants.

"Double mutant is not a scientific term. It is just another mutant which seems to be unique to India," said Ramanan Laxminarayan, founder of the Center for Disease Dynamics, Economics & Policy in New Delhi.

"Is there a reason to be worried about this particular variant? Not as yet, because we have no evidence that these variants are more transmissible or more lethal than what we already have," he added.

About 20 per cent of the samples that contained the new variant in Maharashtra were found in the city of Nagpur, a key commercial and logistics hub, the director of the National Centre for Disease Control, Sujeet Kumar Singh, told a news conference.

VACCINES

The variant is evolving, Singh said, adding that nine such samples were also found in New Delhi, which has seen a steady rise in infections over the last few weeks.

India's two approved vaccines - one developed by AstraZeneca and Oxford University, and the other a homegrown shot from Bharat Biotech - are effective against variants of the virus first identified in Britain and Brazil, health officials said.

On Wednesday, India reported 47,262 new infections over the previous 24-hour period, the highest since early November, taking its overall tally to 11.7 million. Only the United States and Brazil have higher caseloads.

The number of COVID-19 deaths in the last 24 hours rose to 275, the most this year, taking the total to 160,441, government data showed.

Several states announced a ban on large gatherings ahead of the Hindu festival of Holi this weekend.

The federal government also announced it was expanding its nationwide inoculation campaign to include everyone above the age of 45 years from April.