TAIPEI, TAIWAN (AFP) - Taiwan's constitutional court said it would scrap an "unfair" law that means prostitutes can be punished but allows clients to go free.

"The law violates the equality principle in the constitution and shall be invalidated within two years," the court said in a statement on Saturday.

"Punishing only the profit-earner in the sex trade but not the payer constitutes unfair treatment," it added.

Under the existing laws, prostitutes face detention of three days or a fine of up to 30,000 Taiwan dollars ($1,300) if they are caught providing sexual services. Their clients go unpunished.

The ruling comes as Taiwan debates whether to decriminalise prostitution or establish special sex zones similar to those in Amsterdam's famed red-light district.

Taiwan's sex industry is estimated to generate annual revenue of up to 60 billion Taiwan dollars.

About 50 prostitutes are licensed nationwide under laws enacted in 1956. However, the government has stopped issuing licences, allowing these permits to be phased out.