Around 120 million girls around the world, close to one in 10, have been raped or sexually assaulted by the time they turn 20, a new UN report has found.

In a global study of violence against children, the child welfare agency UNICEF reveals that one fifth of all murder victims are children and adolescents under age 20.

Homicide is the leading cause of death among boys and young men aged 10 to 19 in Latin American countries including Venezuela, Colombia, Panama and Brazil.

UNICEF says the study entitled "Hidden in Plain Sight" is the largest-ever study of violence against children, drawing on data from 190 countries.

"These are uncomfortable facts -- no government or parent will want to see them," said UNICEF Executive Director Anthony Lake.

"But unless we confront the reality each infuriating statistic represents -- the life of a child whose right to a safe, protected childhood has been violated -- we will never change the mind-set that violence against children is normal and permissible. It is neither."

Other abuses include bullying, which regularly affected more than one in three schoolchildren aged 13 to 15 worldwide.

And as for violent discipline, the study found that about 17 percent of youngsters in 58 countries were subject to severe forms of physical punishment, including being hit on the head, ears or face or being hit hard and repeatedly.

The UN report also tackles the mindsets it says perpetuate and justify such violence.

It recommended six strategies for preventing violence against children. They include "supporting parents and equipping children with life skills; changing attitudes; strengthening judicial, criminal and social systems and services; and generating evidence and awareness about violence and its human and socio-economic costs, in order to change attitudes and norms."