Russia's state statistics agency on Friday said at least 7,444 people died in May due to the coronavirus, a figure more than double that previously reported by the country's health officials.
Russia came in for criticism in May when it was reporting very few deaths in comparison to other European countries.
Officials attributed the low figures to Russia's rapid response to the pandemic.
The country's health authorities, which have been giving daily figures since March, earlier said that 3,633 people died from the coronavirus in May.
However the state statistics agency, which gives demographic data with a delay, on Friday gave vastly different numbers for that month.
It said the coronavirus was either confirmed or assumed as the “main cause of death” for 7,444 people who died in May.
A further 5,008 people who had a coronavirus diagnosis died of other diseases, though the virus was the “catalyst” in the deaths of 1,530 in this group.
The agency said the total number of deaths this May was 172,914 across Russia, which was more than 18,000 greater than the same month last year.
The head of the Rosstat agency Pavel Malkov said the death rate increased by nearly 12 percent in May year on year.
“The death rate increased in 55 regions, and the biggest increase was in regions that were first to face the coronavirus,” he said in a televised briefing.
Deputy prime minister Tatyana Golikova conceded that the coronavirus was the “main reason for the increase.”
Differences in figures have been explained by differing methodology, and the news on May data follows similar discrepancies in April data.
In late May, regions began to use a different methodology which broadened the approach and included more deaths in the coronavirus figure.
Russia on Friday reported 713,936 cases of infection and 11,017 total deaths.
The country has been gradually lifting restrictions. Moscow will open its cinemas and theatres on August 1, mayor Sergei Sobyanin said.