Iran's official death toll from the new coronavirus rose by 92 to reach 4,869 on Thursday but a parliamentary report said the actual number could be much higher.
Health Ministry spokesman Kianush Jahanpur, speaking on state television, also said the total number of cases of people infected with the coronavirus has reached 77,995.
However, a report by the Iranian parliament's research centre suggested that the coronavirus tolls might be almost twice as many as those announced by the health ministry.
"The assessment is that the actual mortality which has not been accounted for is 0.8 times the official figures. The number of infected cases could be 8 to 10 times the official figures," the report said.
The report said that Iran's official coronavirus figures were only based on the number of deaths in hospitals and those who had already tested positive for the coronavirus.
"To narrow the gap between the officially announced figures and the estimated figures, it is necessary to improve the laboratory capacity of the country," it said.
Iranian health ministry officials have not commented on the report, which was published online.
"Many deaths might have been the result of the coronavirus but not correctly diagnosed as such," the head of the centre, Mohammad Qasemi said on Thursday, according to the semi-official Fars news agency.
Iran is the Middle Eastern country worst-affected by the COVID-19 respiratory disease and has one of the world's highest death tolls.
The government is also concerned that measures to limit public activities could wreck an economy which has already been battered by sanctions.
On Saturday, low-risk business activities resumed across the country, including many shops, factories and workshops, with the exception of Tehran. They will re-open in the capital from Saturday.