The city of Moscow has suddenly doubled its coronavirus death toll from last month.

Media reports and analysts have questioned the accuracy of Russia's mortality figures for the virus.

Under its initial methodology, Moscow's Health Department had attributed 636 deaths to COVID-19. But on Thursday, the department announced that 1,561 deaths in April could be linked to COVID-19.

It attributed the revision to an alternative counting method that takes into account "debatable cases."

The department said the newly counted deaths include 756 coronavirus patients who tested positive but who died of other causes and 169 people who tested negative but were still suspected to have the virus.

Even with the revision, Moscow's death rate from the coronavirus is well below other major cities, including New York and London.

Nationwide, Russia has attributed less than 5,000 deaths to COVID-19, even as its infection rate continues to rise to more than 380,000 cases, according to data compiled by Johns Hopkins University.

The apparent discrepancy has raised questions among journalists and analysts over the legitimacy of those numbers.

An independent analysis of Moscow's mortality rate showed a nearly 20% increase in overall deaths for April compared with the previous 10 years. One of the researchers involved told NPRthat it was likely that many of those deaths could be attributed to the coronavirus.

"I think it's safe to say that if you multiply official death count by a factor of three, you will get a more or less true picture," Aleksei Raksha told NPR's Charles Maynes earlier this month.

Media outlets such as The New York Timesand Financial Times have published similar claims.

Russian officials have disputed those suggestions, attributing the country's low mortality rate from COVID-19 to government efforts and a Russian medical practice of certifying a patient's cause of death based on the particular organ that failed.

Moscow's Health Department initially said 60% of deaths among coronavirus patients were due to other causes, apparently using that methodology.

Moscow's revision to its death toll – and methods for tallying COVID-19 deaths – also only count for the city. Other parts of Russia have seen dramatic increases in deaths but still attributea relatively small number to COVID-19.

The Muslim-majority republic of Dagestan, home to some 3 million people, is among them.

In an interview this month, the republic's health minister, Dzhamaludin Gadzhiibragimov, said 29 people died from COVID-19 in spite of 13,000 infections in the region. He also attributed 657 deaths to "community-acquired pneumonia."

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