Spain is being asked to ban children from both watching and participating in bullfighting.
The calls from the UN Committee on the Rights of the Child, citing the 'harmful effects' of the controversial practice.
The committee said: "In order to prevent the harmful effects of bullfighting on children, the Committee recommends that the State party prohibit the participation of children under 18 years of age as bullfighters and as spectators in bullfighting events."
The Spanish government will now consider the recommendation.
While bullfighting remains a popular and financially lucrative cultural activity in Spain, it is also deeply divisive - with many activists highlighting the animal cruelty involved.
Bullfighting can also prove dangerous for matadors and spectators.
Officials in Catalonia imposed a ban on bullfighting in 2010, but it was overturned by Spain's constitutional court in 2016.
The court ruled that the region was unable to ban a "cultural tradition" practiced in other parts of the country.
However, a number of other regions have considered introducing their own bans amid mounting opposition to bullfighting, especially among young people.