Image copyright AFP Image caption Three women named in the lawsuit say a new law targets women only (file picture)

Strippers in Louisiana are suing the US state, claiming a new law banning dancers under the age of 21 from working hinders freedom of expression.

A new state law, that will come into force next week, demands all exotic dancers be 21 or older.

The women behind the lawsuit say the measure breaches the First Amendment by denying them freedom of expression.

They also say the legislation violates an equal protection cause in the constitution by targeting women only.

This is because the law refers to "entertainers whose breasts or buttocks are exposed to view", ensuring that male dancers under the age of 21 are not affected.

All the women in the lawsuit, filed on Thursday in Louisiana, are under the age of 21. They are named only as Jane Doe I, II and III.

The Times-Picayune newspaper, which has seen the details of the lawsuit, says it states that one of the three dancers works in a New Orleans strip club.

It says she has witnessed pimps and prostitutes using the threat of the new law to try to "recruit entertainers who are now lawfully employed, but who will lose their jobs as a result of the Act".

The lawsuit also reportedly states that one of the dancers, an 18-year-old student, had been told by colleagues under the age of 21 they planned to turn to prostitution once they lost their jobs.

The women's lawyer, Harry Rosenberg, was unavailable for comment when contacted by the BBC.

Governor John Bel Edwards signed the legislation last month.

Senator Ronnie John, who supported it, said the move would prevent human trafficking and ensure the safety of women.

The age of consent in Louisiana is 17.