Iran on Sunday reported over 100 new deaths in a single day from the novel coronavirus, for the first time in two months.
In televised remarks, health ministry spokeswoman Sima Sadat Lari announced 107 Covid-19 fatalities in the past 24 hours, raising the overall toll to 8,837.
"It was very painful for us to announce the triple-digit figure," said Lari.
"This is an unpredictable and wild virus and may surprise us at any time," she added, urging Iranians to observe health protocols.
Iran last recorded triple-digit daily fatalities on April 13, with 111 dead.
Lari also announced 2,472 new cases confirmed in the past day, bringing the total infection caseload to 187,427, with over 148,000 recoveries.
There has been skepticism at home and abroad about Iran's official COVID-19 figures, with concerns the real toll could be much higher.
Iran has struggled to contain what has become the Middle East's deadliest outbreak of the illness since it reported its first cases in the Shiite holy city of Qom in February.
But since April it has gradually lifted restrictions to ease the intense pressures on its sanctions-hit economy.
Iranian President Hassan Rouhani on Saturday reproached citizens for failing to observe measures designed to rein in the virus.
Official figures have shown a rising trajectory in new confirmed cases since early May, which the government has attributed to increased testing rather than a worsening caseload.