Iran said on Thursday its death toll from coronavirus had risen to 26, by far the highest number outside China, and the total number of infected people now stood at 245, including several senior officials.

The outbreak prompted authorities to call off Friday prayers in several cities including Tehran, state TV later reported, while the state news agency IRNA said Iran had banned Chinese citizens from entering.

Those infected include Masoumeh Ebtekar, the vice president for women and family affairs, and Deputy Health Minister Iraj Harirchi. Ebtekar's case was said to be mild and she had not been admitted to hospital.

"In the last 24 hours, we have had 106 (new) confirmed cases ... The death toll has reached 26," Health Ministry spokesman Kianush Jahanpur told state TV, calling on Iranians to avoid "unnecessary trips inside the country".

Jahanpur said there were plans to impose some restrictions at Shi'ite Muslim holy sites and cancel some sermons on Friday, the Islamic Republic's traditional day of public prayer.

"But it needs the approval of the president before being carried out," he said, adding that hundreds of people initially suspected of having the virus had tested negative and been discharged from hospital.

Authorities including President Hassan Rouhani said on Wednesday that Iran had no plans to quarantine any cities or districts, despite the sharp rise in numbers in a short time.

However, Jahanpur said the government had extended its closure of cinemas and temporary ban on cultural events and conferences for another week.

The death rate among confirmed cases of the virus has been running at around 10% in Iran compared to around 3% elsewhere.

Mike Ryan, head of the World Health Organization's emergencies programme, said in Geneva that "the most likely factor is obviously this disease came unseen and undetected into Iran; the extent of infection may be broader than we think".

Iran only announced its first infections and deaths from the coronavirus last week.

Ryan said it appeared that, so far, more severe cases had been detected, but that more milder cases would be detected in future: "I don't suspect it has anything to do with clinical care, more to do with surveillance."

Iran's Foreign Ministry said "some 20,000 coronavirus test kits and some other material" would be delivered to Iran on Friday from China.