At least 300,000 children across India are drugged, beaten and forced to beg every day, in what has become a multi million rupee industry controlled by human trafficking cartels, police and trafficking experts said.
Writing in a report which is about to be circulated across the country's police forces, the authors urged law enforcers to carry out greater surveillance of children living on the streets.
According to the Indian National Human Rights Commission, up to 40,000 children are abducted in India every year, of which at least 11,000 remain untraced.
"The police don't think begging is an issue because they assume that the adult with the child is either family or a known person," said co-author Anita Kanaiya, CEO of The Freedom Project India, which works on trafficking issues.
"But for every 50 children rescued there will be at least 10 who are victims of trafficking. And there has to be a constant vigil to identify them," she told the Thomson Reuters Foundation.
Children are sometimes maimed or burned to elicit greater sympathy and get more alms, said the report.
The money they earn is usually paid to the traffickers, or to buy alcohol and drugs.
The report is based on the experiences of police and charities in Bengaluru city, formerly known as Bangalore, in the southern Indian state of Karnataka.
There is a seasonal pattern to begging, local police said. Cities like Bengaluru see a sharp rise in the numbers of children wandering the streets just before festivals or after a natural disaster.
In 2011, Bengaluru police launched "Operation Rakshane" ("To Save"). In coordination with various government departments and charities, they drew up a blueprint to help children forced into begging.
Months before carrying out a series of rescues, they spread out across the city, taking pictures of children on the street, documenting their daily activities and shadowing them back to their homes.
"When we started, we had nothing to prove the connection between begging and trafficking. But we went about meticulously recording any signs of forced labor on the streets of the city," Kanaiya said.
According to inspector general of police, Pronob Mohanty, who spearheaded the operation, teams of police and health workers rescued 300 children on a single day across the city.
The traffickers were arrested and later imprisoned.
"Operation Rakshane is meant to be a template which can be replicated as a model of inter agency cooperation," Mohanty said in the handbook, which includes suggestions for surveillance, data collection and rehabilitation, as well as listing relevant laws.
Kanaiya said: "We are now initiating a planned campaign to take the book to every police headquarter in the country and follow it up with a workshop on child (begging) and rescue operations for policemen."