Iran on Tuesday announced that confirmed coronavirus infections had reached almost 100,000 in the country as fresh cases picked up again after a brief drop in recent days.

"The number of confirmed infections with this disease is now close to 100,000," health ministry spokesman Kianoush Jahanpour said in televised remarks.

"We lost 63 of our countrymen in the past 24 hours, reaching a total of 6,340 deaths from COVID-19 to date," he added.

Jahanpour said that another 1,323 people tested positive for the virus during the same period, bringing the overall number to 99,970. Two-thirds of the fresh cases were "those sampled as outpatients" or family members of those infected, Jahanpour said.

On Saturday, Iran's new daily infections hit their lowest since March 10 but they have picked up again since then.

According to Jahanpour, 80,475 of those hospitalised with the disease since Iran reported its first cases in mid-February have been discharged, while 2,685 are in critical condition. Doubts have been cast over Iran's coronavirus figures by experts and officials both at home and abroad.

Iran has reopened mosques in parts of the country deemed at low risk from the virus after allowing a phased reopening of businesses since April 11. The Islamic republic is using a colour-coded system of "white" for low-risk parts of the country, "yellow" for medium-risk zones and "red" for high-risk areas.

Hamshahri reported that southern provinces such as Sistan and Baluchistan, Hormozgan, Fars and Bushehr had the most white areas. Other provinces are mostly still yellow, while Qom, the virus' epicentre in Iran, was red with a "rising trend" of new infections.

Ministry officials have warned that an area being "white" does not mean "the situation is normal" there, and that the condition can reverse at any time.