Italy's competition watchdog on Friday fined two companies owned by the fashion entrepreneur and Instagram star Chiara Ferragni €1 million for "unfair commercial practices" over her endorsement of a cake marketed as raising money for charity.

The pandoro cake "designed" by Ferragni for the food group Balocco went on sale in November 2022, purportedly to raise funds for the treatment of children with bone cancer in a hospital in Turin.

In fact, Balocco had made a fixed-sum donation of €50,000 to the Regina Margherita Hospital months earlier, the competition authority said in a statement.

The firms that manage Ferragni's activities, Fenice and TBS Crew, made more than €1 million in the deal "without paying anything" to the hospital, it said.

Fenice was fined €400,000  and TBS Crew was fined €675,000. Balocco, based near Turin in northwest Italy, was fined €420,000.

The authority accused the three companies "of having implemented an unfair commercial practice by publicising the 'Pandoro Pink Christmas', designed by Chiara Ferragni, implying to consumers that in buying it, they would contribute to a donation" to the hospital.

The pandoro cost around 2.5 times a non-branded version, a markup that "contributed to misleading customers, reinforcing their perception of being able to contribute to the donation".

Ferragni, who has almost 30 million followers on Instagram, came to prominence with a fashion blog before launching her shoe collection.

She went on to collaborate with several fashion brands, including Dior and Chanel, and is part of one of Italy's most famous celebrity couples with her husband Fedez, a rapper and music producer.