The country's mining boom has created an underground economy in Queensland, which mostly caters to the sexual needs of workers, police authorities in the state said.

Most of the sex workers, according to Mount Isa police district Inspector Paul Biggin, were believed to be originating from the neighbouring Southeast Asian nations, compelled by poverty to try their luck out of their homelands only to be exploited by criminal organisations.

Insp Biggin said business was so good that the young women were being boldly advertised on local newspapers by their handlers "and they are coerced or threatened into," forced prostitution.

The problem is presently prevalent in Queensland's inner cities and the towns nearest to the state's expanding mining projects, the Mount Isa police executive told The Australian in an interview.

These 'foreign workers' were believed to have been smuggled into the country and can be identified easily, Insp Biggin said.

The trafficked women can hardly speak English and were not highly educated, thereby leaving them more vulnerable to "being trafficked for sex, from one mining town to the next."

"They are working on a fly-in, fly-out basis, two weeks here, two weeks in the next town and so on," the police official said in describing the normal 'work routine' that the helpless women were being subjected to.

It also understood that the women were being watched over by enforcers from criminal rings, making sure that the sex workers will remain silent in the event that police authorities learned of specific operations and busted them, Insp Biggin said.

Apart from being physically harmed, police investigators also discovered that some of the victims feared retaliation on their families if they spilled the beans on sex ring operators.

But Insp Biggin is doubtful if the women will trust police authorities even if they know anything about the illegal operations.

"They are being told they cannot go to the police because in the countries they come from, the police might even be part of the problem," the police officer was reported by the Australian Associated Press (AAP) as saying.

It is a common belief that in a number of Southeast Asian nations, where the women came from, criminal syndicates that deal with drug and prostitution businesses operate under the protection of local and police officials.

In many cases too, young girls were being sold by their families fully aware of the fate that await them.

Insp Biggin has admitted that inner workings by the criminal groups running the mobile sex workers proved difficult in dealing with the emerging problem as many of the women have been 'pre-conditioned' not to cooperate with authorities.

In most cases, police probes encounter a blank wall, the police official lamented.

"Whenever we have an operation to target them, they come into the station and you can see that they are being controlled mentally and physically and it's very difficult to get them to open up to authority and enable us to help them," Insp Biggin said.