NEW DELHI - India reported a record rise in Covid-19 deaths on Thursday (June 10) with 6,148 fatalities after the state of Bihar revised its toll from the disease and increased its total tally by more than 70 per cent.

It added 3,951 backlog fatalities as well as 20 fresh deaths to its toll, which had stood at 5,458 on Wednesday.

The adjustment of Bihar's death toll has further strengthened the widely held suspicion that India's official tally, which was 359,676 on Thursday, grossly underestimates the extent of Covid-19 fatalities.

Bihar's revised figure includes deaths reported at private hospitals, those that occurred while in transit to health facilities and under home isolation, as well as those who died of post-Covid complications after testing negative, Mr Pratyaya Amrit, additional chief secretary at Bihar's Health Department, told a media briefing on Wednesday.

"These deaths had remained unaccounted for earlier," he added.

The adjustment was carried out through a 20-day verification exercise following an order of the Patna High Court, which asked for an audit of casualties in the state during India's second wave of Covid-19 amid allegations that the state government was hiding the scale of infections and deaths.

The revised figure set off a political controversy with opposition figures calling for such audits in other states governed by the Bharatiya Janata Party, including Uttar Pradesh, Madhya Pradesh and Gujarat.

India's total caseload stood at nearly 29.2 million on Thursday after rising by 94,052 in the past 24 hours.

The country has recorded fewer than 100,000 daily new cases for three consecutive days.

Active cases stand at a little more than 1.16 million, according to government data.

Under-counting of deaths as well as cases has happened because testing and medical facilities are inadequate in rural areas, which are home to around 65 per cent of the Indian population.

Many have fallen ill and died of "Covid-19-like" symptoms at home in villages without being tested for the coronavirus.

In urban areas, under-reporting occurs because bodies of many suspected Covid-19 victims at hospitals are not tested and left out of the official count.

Even deaths of certain Covid-19 patients are at times attributed to other complications the patient may have had such as chronic hypertension or diabetes.

Dr Sunil Kumar, secretary of the Bihar chapter of the Indian Medical Association, said under-counting happened not just because individuals died from Covid-19 in far-flung areas without being tested but also because tests for many Covid-19 patients came back negative.

Reports around the peak of the second wave suggested up to 20 per cent symptomatic Covid-19 patients were testing negative through reverse transcription polymerase chain reaction (RT-PCR) tests for reasons that included delayed testing, human error and poor quality of kits.

Among the patients who died in May from Covid-19 under Dr Kumar's treatment were two individuals whose RT-PCR test results showed up as negative.

However, computed tomography scans of their lungs showed abnormalities that were classic symptoms of Covid-19, Dr Kumar told The Straits Times.

"The government should include such deaths as well in its list of fatalities," he added.

Bihar's Health Department has announced that such patients will be eligible for a compensation of 400,000 rupees (S$7,250) meant families of those who die from Covid-19.

The High Court of Uttarakhand has also asked the state government to conduct an audit of deaths that occurred during the second wave of the coronavirus in the state. The Himalayan state has reported 6,849 Covid-19 fatalities.

Concerns around under-reporting of deaths in India have been around since the pandemic began.

They were, however, heightened during the second wave in April and May this year as crematoria overflowed with those killed by Covid-19 and hundreds of bodies were either dumped in rivers or buried in shallow graves on their banks.

Media reports in India even cited wide discrepancies between the figures of local Covid-19 funerals and official data on fatalities released by the local jurisdiction.

An analysis by The New York Times in May suggested that deaths in India could be as high as 1.6 million in a "more likely" scenario and 4.2 million in a "worse" scenario, figures that were strongly questioned by government officials.

On May 31, Peru almost tripled its official Covid-19 death toll to 180,764, following a government review, making it the country with the worst per capita death rate, according to data maintained by Johns Hopkins University.

Mexico also revised its figures in March, indicating that the actual number of deaths caused by the coronavirus was 60 per cent higher than previously reported.

More than 321,000 people are now believed to have died from Covid-19 in the country.