The Scarlet Alliance, representing Australia's sex workers, and the Asia Pacific Network of Sex Workers, say a recent law change in Cambodia equates all sex work with trafficking.

That had led to closures of brothels and widespread human rights abuses against sex workers, they said.

The new laws had simply moved sex work underground, in an unsafe, unregulated environment, alliance president Elena Jeffreys told AAP.

"Hundreds of sex workers have also been arrested, detained, and have faced violence and sexual assault in detention.

"Sex workers who are HIV positive have been unable to access their medication, which is placing their lives at risk."

The Cambodian government overlooked the distinction between sex work and trafficking, Ms Jeffreys said.

"The outcome of the law has been to abolish the entire sex industry in Cambodia.

"It is unacceptable and it is a human rights abuse that trafficking hasn't been approached with a more sensitive and more sophisticated set of laws."

The entire HIV response in Cambodia had broken down as a result of the law change, Ms Jeffreys said.

The Cambodian government needed to repeal and review the anti-trafficking laws and decriminalise sex work.

"This would go a long way to both granting sex workers human rights, and preventing trafficking in Cambodia."

Source: The Sydney Morning Herald, Australia