An Iranian official on Monday denied rumors about the health of Supreme Leader Ayatollah Ali Khamenei, the country's semi-official Fars news agency reported.

"Whether the enemy likes it or not... the Leader is in good health and cheerful, carrying out his duties according to the usual routine," tweeted Mehdi Fazaeli, an official at Iran's Office for the Preservation and Publication of the Works of the Leader of the Revolution.

On Saturday, American magazine Newsweek, citing an Iranian journalist, reported that "Khamenei has transferred power to his son Mojtaba over health concerns."

Rumors of Khamenei's worsening health had circulated online after claims on social media that were carried by foreign news outlets.

According to Iran's Tasnim news agency, this had started with a "fake" tweet making the claim on an Arabic account described as being "owned by a separatist individual based in London."

Khamenei's last public appearance was on November 24, when he met Iran's top officials, with videos of the meetings aired by state television.

The 81-year-old leader underwent a successful prostate cancer operation in 2014.

State TV on Monday denied reports of a meeting of the Assembly of Experts, an 88-strong body of elected clerics responsible for appointing and monitoring the supreme leader.

It said a picture circulating on social media, purportedly of the news channel reporting such a meeting, was fake.

(With input from agencies)