A United Nations report has revealed a "shocking" picture of physical, sexual and psychological violence against children across the globe.

The report, released by UN Secretary-General Kofi Annan's office on Thursday, concludes that violence against children is widely accepted as normal and occurs in every country, every society and every social group.

"We knew children were victims of violence, but even so it was very surprising and shocking that it was so widespread," Mehr Khan Williams, the UN Deputy High Commissioner for Human Rights, told reporters Thursday.

"It cuts across cultures, income levels, education levels. No country is immune from it."

The study, which says such abuse is often socially approved or even legal, is the result of four years of research.

At least 106 countries still allow physical punishment in schools and up to 275 million children witness domestic violence annually, the report says.

"Violence against children in the family may frequently take place in the context of discipline and takes the form of physical, cruel or humiliating punishment," the report adds.

"Harsh treatment and punishment in the family are common in both industrialized and developing countries."

In a statement released with the report, Louise Arbour, UN High Commissioner for Human Rights, said "legalized violence against children in one context risks tolerance of violence against children generally."

"Violence against children is a violation of their human rights, a disturbing reality of our societies," she added.

Sexual abuse

The report said World Health Organization data estimated that in 2002 some 150 million girls and 73 million boys were subjected to forced sexual intercourse and other forms of violence, while 53,000 were killed.

"Many people, even children, accept violence as an inevitable part of life," said independent expert Paulo Sergio Pinheiro in the report.

Data showed there were 218 million child labourers in 2004, of whom 126 million did hazardous work, the report said.

There are also as many as 250,000 child soldiers around the world. In Congo, more than 11,000 children are missing and believed to be either forced into armies and militias or used as sex slaves.

It estimates that up to 140 million women and girls have undergone genital mutilation.

"I urge states to prohibit all forms of violence against children, in all settings, including all corporal punishment, harmful traditional practices -- such as early and forced marriages, female genital mutilation and so-called honor crimes -- sexual violence and torture and other cruel, inhuman or degrading treatment or punishment," Pinheiro said.

Such violence can leave serious long-term psychological scars which result in increased risky sexual behaviour, substance abuse and violence towards others in adulthood, the report says.

One of the biggest hurdles to exposing such violence is reluctance to shed light on what is going on inside the home, said Amaya Gillespie, director of the secretariat of the UN secretary-general's study on violence against children.

"Probably the biggest barrier to that is the lack of leadership and not least in the political circles. There's really a reluctance to look at home and family, as if there's some kind of privacy barrier there," Gillespie said, appearing on CTV's Canada AM.

The UN is calling on every country to have a national strategy to outlaw violence against children and ensure their rights are protected.