Italy's competition authority on Thursday fined TikTok 10 million euros (nearly $11 million), saying the hugely popular video app had failed to sufficiently protect minors.

"The company has failed to implement appropriate mechanisms to monitor content published on the platform, particularly those that may threaten the safety of minors and vulnerable individuals," the AGCM watchdog said in a statement.

"Moreover, this content is systematically re-proposed to users as a result of their algorithmic profiling, stimulating an ever-increasing use of the social network."

The fine has been imposed on three units of China's Bytedance group, namely Ireland's TikTok Technology, TikTok Information Technologies UK and TikTok Italy.

The watchdog said TikTok had not fully complied with guidelines it had advertised to reassure consumers the app was a "safe" space.

"In fact, the guidelines are applied without adequately accounting for the specific vulnerability of adolescents, characterised by peculiar cognitive mechanisms from which derive, for instance, the difficulty in distinguishing reality from fiction and the tendency to emulate group behaviour," it said.

It added that "potentially dangerous" content is promoted through TikTok's recommendation system.

It highlighted the "French scar challenge", where children pinch their cheeks violently to create bruising, a phenomenon explained by numerous tutorials on TikTok that has caused concern in the education and health sectors.

In a statement, TikTok said it disagreed with the watchdog's decision.

"There were only on average 100 daily searches in Italy for so-called 'French Scar' content before the AGCM announced its investigation last year," it said.

"We have for a long time limited the visibility of this content to the under-18s, and made it ineligible in the 'For You' feed.