MOSCOW (Reuters) – Russia’s second biggest city of St. Petersburg recorded a death rate last month 32% higher than last year, official data showed on Wednesday, suggesting that there may be more people dying of COVID-19 than are being reported.

The St. Petersburg city government said on Wednesday that it had issued 6,427 death certificates in May, compared to 4,875 in the same month last year.

That was the highest monthly death rate in the city for at least a decade. However, the confirmed death toll from the novel coronavirus in May was just 171 people.

Russia’s official coronavirus death rate of 1.2% is one of the lowest in the world, partly because it does not count many people who had other severe illnesses but at the time of their deaths were also infected with the virus.

“Pretty much all recent pneumonia deaths can… be linked to the coronavirus situation,” said Alexei Yakovlev, the former chief doctor at a St. Petersburg hospital that treats the coronavirus.

“There have never been so many cases of pneumonia, not ever. And since there’s no other flu or infection going around right now, it leads one to believe that (the numbers) are due to the coronavirus,” Yakovlev, who also heads the infectious diseases department at St. Petersburg State University, told Reuters.

The Russian health ministry declined to comment on the data and St. Petersburg’s health committee did not immediately respond to written questions.

Since the start of the coronavirus outbreak, St. Petersburg has recorded 17,069 coronavirus cases and a total of 240 deaths.

The city of Moscow, which has more than 40% of all of Russia’s confirmed 423,277 coronavirus cases, earlier doubled its official coronavirus death toll for April after criticism for undercounting.