Iran said Tuesday a British-Iranian woman jailed in Tehran is "in perfect health" after the dual national reportedly expressed fears of contracting the new coronavirus behind bars.

Nazanin Zaghari-Ratcliffe, who was arrested at Tehran airport in April 2016, is serving a five-year term for sedition at Evin prison in the Iranian capital.

Iran's judiciary spokesperson Gholamhossein Esmaili said Zaghari-Ratcliffe was "in perfect health".

"Yesterday she talked to her family by phone. There has been news about her recently that was fake news," he said on state television.

On Saturday her husband Richard Ratcliffe said that the 41-year-old detainee believed she had contracted the COVID-19 illness that has claimed 77 lives in the Islamic republic.

Strange cold

Ratcliffe said she had complained to him in a phone call that prison authorities were refusing to test her for the virus, despite her suffering from a worsening "strange cold".

His wife has repeatedly denied the charges against her.

She was arrested after visiting relatives in Iran with their young daughter.

At the time, she worked for the Thomson Reuters Foundation, the media organisation's philanthropic arm.