Iran's nuclear chief Ali Akbar Salehi has tested positive for the novel coronavirus, state media reported on Sunday, as the country announced a new record high in daily fatalities.

Salehi, a vice president and the head of the Atomic Energy Organisation of Iran, had been under quarantine and resting at home since the test on October 3, state news agency IRNA reported.

Another vice president, Mohammad Bagher Nobakht, said on Saturday on Twitter that he was "under medical observation" after contracting the virus during the past week.

IRNA said both Salehi and Nobakht were in a "good" health condition on Sunday.

Deaths and infections from the virus have been on a sharply rising trajectory in Iran since early September.

The health ministry said another 251 people died of COVID-19 in the past 24 hours, yet another record high for a single day in the Islamic republic.

Total virus infections since Iran reported its first cases in February crossed the 500,000 mark on Sunday, with 3,822 new cases confirmed.

Overall, COVID-19 has killed 28,544 and infected 500,075 people in the Middle East country hardest hit by the pandemic.

Iran on Saturday started imposing fines for the first time for breaches of health regulations in the capital as part of efforts to contain the virus.

Offences that can be fined include refusal to quarantine while sick and failing wearing a mask in a public space. Businesses can also be fined for failing to ensure customers wear masks.