Iran announced more than 39,000 new Covid cases on Tuesday, the highest in a single day in the Middle East country worst hit by the pandemic.

The health authorities in Iran said another 378 people died of coronavirus and 39,019 tested positive in the past 24 hours.

According to official figures widely believed to underestimate the real toll, the virus has killed 91,785 people in the Islamic republic out of 3,979,727 cases of infection.

Choked by US sanctions that have made it difficult to transfer money abroad, Iran says it is struggling to import vaccines for its 83 million population.

More than 10.7 million people have been given a first vaccine dose, while 2.8 million have received the necessary two jabs, the health ministry said Tuesday.

Iran's supreme leader Ayatollah Ali Khamenei on Monday ordered that "necessary measures" be taken to contain what the government warns is a "fifth wave" of the country's outbreak.

The country has avoided imposing a full lockdown on the population, and instead resorted to piecemeal measures such as temporary travel bans and business closures.