India's crematoria and burial grounds are being overwhelmed by the devastating new surge of coronavirus infections tearing through the country, depleting the supply of life-saving oxygen to critical levels and leaving patients to die while waiting to see doctors.

For the fourth straight day, on Sunday India set a global daily record of new infections, spurred by the emergence of a new variant that has undermined the government's premature claims of victory over the pandemic.

The 349,691 confirmed cases over the past day took India's total to more than 16.9 million, behind only the United States.

The Health Ministry reported another 2,767 deaths in the past 24 hours, pushing India's Covid-19 fatalities to 192,311.

Experts say that toll could be a huge undercount, as suspected cases are not included, and many deaths from the infection are being attributed to underlying conditions.

The crisis unfolding in India is most visceral in its graveyards and crematoria, and in heartbreaking images of gasping patients dying on their way to hospital due to lack of oxygen.

Burial grounds in the Indian capital, New Delhi, are running out of space and bright, glowing funeral pyres light up the night sky in other badly hit cities.

In central Bhopal city, some crematoria have increased their capacity from dozens of pyres to more than 50, but officials said there are still long waits.

At the Bhadbhada Vishram Ghat crematorium, workers said they cremated more than 110 people on Saturday, even as government figures in the city with a population of 1.8 million put the total number of deaths at just 10.

"The virus is swallowing our city's people like a monster," said Mamtesh Sharma, an official at the site.

The unprecedented rush of bodies has forced the crematorium to abandon individual ceremonies and rituals that Hindus believe release the soul from the cycle of rebirth.

"We are just burning bodies as they arrive," said Mr Sharma. "It is as if we are in the middle of a war."

The head gravedigger at New Delhi's largest Muslim cemetery, where 1,000 people have been buried during the pandemic, said more bodies are arriving now than last year.

"I fear we will run out of space very soon," said Mohammad Shameem.

The situation is equally grim at unbearably full hospitals, where desperate people are dying in queues, sometimes on the roads outside, waiting to see doctors.

Health officials are scrambling to expand critical care units and stock up on dwindling supplies of oxygen. Hospitals and patients alike are struggling to procure scarce medical equipment that is being sold at inflated prices.

The crisis is in direct contrast with government claims that "nobody in the country was left without oxygen" in a statement made at Delhi High Court on Saturday by India's Solicitor General, Tushar Mehta.

The breakdown is a stark failure for a country whose prime minister declared victory over Covid-19 in January, and which boasted of being the "world's pharmacy", a global producer of vaccines and a model for other developing nations.

Caught off guard by the latest deadly spike, the federal government has asked industrialists to increase the production of oxygen and other life-saving drugs in short supply. But health experts said India had an entire year to prepare for the inevitable - and failed to do so.

Dr Krutika Kuppalli, assistant professor of medicine in the division of infectious diseases at the Medical University of South Carolina, said the Indian government has been "very reactive to this situation rather than being proactive".

She said the government should have used the last year, when the virus was more under control, to develop plans to address a surge and "stockpiled medications and developed public-private partnerships to help with manufacturing essential resources in the event of a situation like this".

"Most importantly, they should have looked at what was going on in other parts of the world and understood that it was a matter of time before they would be in a similar situation," Dr Kuppalli said.

She called the government's premature declarations of victory over the pandemic a "false narrative", which encouraged people to relax health measures when they should have continued strict adherence to physical distancing, wearing masks and avoiding large crowds.

Prime Minister Narendra Modi is facing mounting criticism for allowing Hindu festivals and attending mammoth election rallies that experts suspect accelerated the spread of infections.

His Hindu nationalist government is trying to quell critical voices.

On Saturday, Twitter complied with the government's request and prevented people in India from viewing more than 50 tweets that appeared to criticise the administration's handling of the pandemic. The targeted posts include tweets from opposition ministers critical of Mr Modi, journalists and ordinary Indians.

A Twitter spokesman said it has powers to "withhold access to the content in India only" if the company determines the content to be "illegal in a particular jurisdiction".

The company said it had responded to an order by the government and notified people whose tweets were withheld.

India's Information Technology ministry did not respond to a request for comment.