Thousands of people are working illegally in Asian nations

John Miller, director of the US State Department's anti-people trafficking office, said the trade in humans was a "modern-day form of slavery".

During a visit to Indonesia, he said people trafficking was an abuse of human rights and provided income for international criminal gangs.

The US estimates that at least 800,000 people a year are trafficked across international borders.

Victims are often duped by organised gangs offering well paid jobs in the West. When they arrive, having already paid large sums of money to the traffickers, they are threatened with exposure to the immigration authorities and forced to work for a pittance.

In many cases, woman and children are forced to work as prostitutes.

Mr Miller said countries that qualified for the US anti-trafficking fund would get money for law enforcement training, education and assistance to victims.

During a visit to a hospital in the Indonesian capital Jakarta, which treats trafficking victims, Mr Miller praised Indonesia's efforts to end people smuggling. But he urged the government to pass anti-trafficking legislation that has been pending since last year.

"I understand the president and government support this legislation," he said. "I hope the legislation is passed in the next few months."

From Indonesia, Mr Miller headed to Malaysia. His tour will also take in Singapore, Cambodia, and Japan.