NEW YORK (THOMSON REUTERS FOUNDATION) - Children will no longer be classified as prostitutes in the US state of California after a new law decriminalised prostitution for minors in a move praised by child rights campaigners.

Coming on the back of a public campaign coined "There is No Such Thing" as a child prostitute, crimes of solicitation and prostitution will no longer apply to anyone aged under 18.

Under-age victims of sex trafficking are to be referred to child welfare agencies.

The law was among several signed by Governor Jerry Brown this week to boost protections for children forced into sex trafficking.

"The passage of these critical laws marks a clear shift in the public perception of sexually exploited children as victims rather than criminals," said Yasmin Vafa, executive director of Rights4Girls that launched the "No Such Thing" campaign.

"We are thrilled that media and lawmakers alike are beginning to understand that there is no such thing as a child prostitute," she said in a statement.

Other new measures include allowing prior convictions by trafficking victims to be eliminated and the records sealed, and allowing children under age 16 to testify remotely by closed-circuit television rather than open court in some cases, according to the Los Angeles Times.

The laws come amid debate over redefining prostitution as sex trafficking, in which victims are coerced and exploited, do not choose sex work voluntarily and cannot leave.

Children in particular are too young to consent, advocates say.

Others argue prostitution is a matter of free choice and valid work that should be decriminalised so that sex workers are not punished.

In the United States, more than 1,000 children are arrested each year on charges of prostitution, according to Rights4Girls.

More than a dozen other states have similar laws decriminalising prostitution for children, but the measure in California is significant because it is one of the largest US states and accounts for many of the arrests of children in the country, according to a spokeswoman for Rights4Girls.

Under US federal law, the prostitution of children is considered a form of human trafficking, according to the Department of Justice.