A landmark national survey of thousands of children in India has found that almost half of them have suffered some form of physical, sexual or economic abuse.

The survey of 17,000 children was carried out across India and is the largest child-abuse study ever conducted in the country.

The dramatic findings come a few months ahead of plans by India's parliament to debate new child protection laws.

If the results of this survey are any indication, 11-year-old Shanoat and his eight-year-old brother Sarfarad are typical of many children in India.

They spend their days cleaning out empty train cars at Kolkata's main railway station, on the constant lookout for food left by passengers. And almost every day they have run-ins with the police.

"The cops don't care who you are," Shanoat told CBC's Michael McAuliffe. "If they don't like something they'll hit you. In the last year, I've been hit by the police maybe a thousand times."

According to the survey, 40 per cent of the children reported being beaten at some point in their lives.

In New Delhi, 71 per cent of the children surveyed said they had been beaten by authority figures, and in more than half those cases, the beatings were severe enough to cause bleeding.

It's a national pattern of child abuse that outreach worker Boulanat Goush said is taking a toll on India's youngest generation.

"Many of the kids here at the Kolkata train station, for example, have no families," Goush said. "The authorities constantly hit them around here. At the end of the day, they can't help but be traumatized."

Perhaps even more disturbing is the study's finding that one in four Indian children taking part in the survey had complained of being sexually abused.

"There are all kinds of sick bastards around here who try to get you to do things," Shanoat said. "But I won't. I know they do things with some of the other boys, but really, we don't like to talk about it."

The year-long study was conducted in 13 states by the non-governmental group Prayas and backed by the United Nations' child welfare agency UNICEF and Save the Children Fund.

In a country of a billion people, where 40 per cent of the population is now under the age of 18, the study's findings come at an opportune time.

Later this year, India's parliament is likely to consider a new child protection bill that would for the first time ever compel parents, doctors, teachers and the police to report instances of child abuse to the authorities.