Iran said Wednesday that the novel coronavirus has killed 147 more people, a new single-day record in the virus-stricken country that raised the overall toll to 1,135.

"Now everyone knows about this disease, and what is very strange is that some don't take it seriously," Deputy Health Minister Alireza Raisi said in a televised news conference. "If people help, we can control it, and if not, then expect it to last more than two months."

Iran's President Hassan Rouhani defended the response to the new coronavirus outbreak by his administration, which has yet to impose a lockdown to stop the disease spreading.

The COVID-19 outbreak in sanctions-hit Iran is one of the deadliest outside China, where the disease originated.

"Some ask why the government isn't intervening, but I think we have intervened significantly," the president said on Wednesday. "Great things have been done (including) measures no other country has taken," he said in televised remarks after a weekly meeting of his cabinet. "We will get past these hard days," Rouhani added, flanked by ministers wearing face masks.

Since it announced its first two deaths in the holy Shiite city of Qom on February 19, Iran has taken a series of steps to contain the virus. However it has yet to impose any lockdowns and the outbreak has spread to all 31 of the country's provinces.

Few officials have directly commented on why a lockdown has not been imposed. But Tehran's mayor has said the economy may not be able to handle the cost of doing so, especially while it is under crippling US sanctions.

"In a normal situation and a good economy, we could have imposed a lockdown," Pirouz Hanachi was quoted as saying by Mehr News agency. "But what comes next, like providing necessary goods or compensating for losses across Iran, is not possible, so a complete lockdown cannot be done," he added.

The United States withdrew from a landmark nuclear deal and began reimposing punishing sanctions on Iran in 2018, blocking banking transactions and oil sales, among other sectors. To contain the virus, Iran has closed schools and universities until early April and also four key Shiite pilgrimage sites, including Fatima Masumeh shrine in the country's epicentre, Qom.

It has also discouraged travel for the Iranian New Year holidays starting this week, cancelled the main weekly Friday prayers and temporarily closed parliament. Rouhani said his administration had "talked to the people honestly" about the virus outbreak.

Rouhani slammed what he called "lies and propaganda" spread online and said there were no "delays" by authorities in announcing infections or testing people. Official tolls, which are given every 24 hours by the health ministry, have usually lagged behind reports by local media and have sometimes been contradicted by provincial authorities.

Provincial medical universities have at times reported higher fatalities than officially reported, but those have been disputed as being "severe respiratory illnesses" rather than directly caused by the coronavirus.