An official close to Iran's Supreme Leader Ayatollah Ali Khamenei has denied rumours on social media that the top authority's health was deteriorating, the semi official Fars news agency reported on Monday.

"By the grace of God and with the good prayers of devotees, the Gentleman (Ayatollah Khamenei) is in good health and is busy vigorously carrying out his plan according to his routine," Fars reported, quoting a tweet by Mehdi Fazaeli.

Fazaeli has worked in an office publishing Khamenei's work.

Some unconfirmed reports on Twitter suggested that Khamenei had transferred his duties to his son because of concerns over his health. Some users on social media also said he had passed away.