Khomeini died in 1989 but remains the subject of adulation by the clerical leadership under successor Ayatollah Ali Khamenei.

The house was later turned into a museum commemorating Khomeini. It was not immediately clear what damage it sustained.

But Iran's Tasnim news agency later denied there had been a fire, saying the "door of the historic house is open to visitors".

"The counter-revolutionary media tries to create turmoil by spreading lies and false information. The burning down of Imam Khomeini's historic house, a place with with spiritual value to Iranians, was one of those lies," the deputy goveronor of Markazi province Behnam Nazari was quoted as saying.

The protests sparked by the death of Mahsa Amini, who had been arrested by the morality police, pose the biggest challenge from the street to Iran's leaders since the 1979 revolution.

They were fuelled by anger over the obligatory headscarf for women imposed by Khomeini but have turned into a movement calling for an end to the Islamic republic itself.

Images of Khomeini have on occasion been torched or defaced by protesters, in taboo-breaking acts against a figure whose death is still marked each June with a holiday for mourning.