Young Asian children were kidnapped from the street and forced to work as beggars, some with their arms or legs deliberately broken to make them look more appealing. Others were lured into drugs, crime and prostitution.

All of these abuses are claimed to have been witnessed by Surachai Sukkieo, on the streets of the Thai capital Bangkok.

He says they're the reason he helped found the Baan Nokkamin Foundation, which cares for street children across Thailand.

Now it's claimed there are new types of abuses. Children put "on display" at orphanages to entice donations from visitors.

Rights campaigners and children's charities say Asian children are being used as "tourist attractions" for western holiday-makers.

There's concern from the U.S. State Department and charities including Re-Think Orphanages, Forget Me Not and Lumos that so-called "orphanage tourism" is growing in places like Thailand, Cambodia, Myanmar, Indonesia and Nepal.

Australia has become the first country to criminalize "orphanage trafficking" – the shoddy practice of luring children to orphanages for gain.

Sukkieo says he's aware of these activities, and worse.

"Yes, some orphanages use children just to get money. But there are worse cases – bad people who break children's arms and legs to make them look more appealing when they send them out begging," he said.

"I would say don't give money to children or you may be helping mafia gangs – give money directly to children's organizations."

All this comes amid the growing popularity of "voluntourism," where people spend their holidays helping others.

But one of the largest volunteer organizations says it never places volunteers in orphanages.

"It's just like you're using vulnerable children to raise funds – which is unethical in our opinion," said Matumon Katerenchuk, program development specialist at the Asia-Pacific headquarters of Voluntary Service Overseas in Bangkok.

"The children should not be in those kinds of orphanages."

It's estimated that worldwide up to 80 percent of children in orphanages actually have a parent who could look after them.

But often they are sent to institutions by poor families in the hope they will receive a better start in life.

Many organizations – including VSO – would like to see an end to orphanages altogether, with children returned whenever possible to their own families or cared for in the communities where they live.

But Surachai Sukkieo, from the Baan Nokkamin Foundation, believes there is still a place for properly-run and regulated homes, though he says his orphanages are run more like foster-homes than institutions – where groups of up to 10 children are looked after by married couples in a family-type unit.

Baan Nokkamin Orphanage says it ensures none of its children are ever exploited, and it's open to independent inspections at any time. The youngsters in their care are given a full education, some even progressing to university.

But in unregulated homes, the trafficking of children to make money, say campaigners, is nothing less than modern-day slavery.