London - The British government announced plans Wednesday to clamp down on prostitution involving women who are controlled by pimps or have become victims of so-called sex-slave trafficking.

Paying for sex with prostitutes "controlled for another person's gain" is set to become a criminal offence in England and Wales, Home Secretary Jacqui Smith said.

Anyone who knowingly paid "illegally trafficked women for sex" could face rape charges, while kerb crawlers could face prosecution for a first offence.

The changes, expected to come before parliament next month, will bring legislation in England and Wales in line with Scotland, where anyone looking to pick up a prostitute faces a fine of up to 1,000 pounds (1,600 dollars).

The measures are aimed primarily at clamping down on the growing "sex trade" involving women being smuggled into Britain from Eastern European countries.

"What I disapprove of is women being exploited in this country, coerced, trafficked into the country, effectively treated as slaves," Smith said.

The government had considered banning paying for sex altogether, said Smith, but realized that there was no public support for such a drastic move.

Under the revised laws, buying or selling sex would remain legal, while "soliciting and pimping" would become a criminal offence.

"My proposal is that men should think twice about paying for sex. Trafficked women don't have a choice; men do," she said.

Smith said up to 70 per cent of prostitutes were controlled by pimps or had been trafficked into the country and the government was working closely with the police on plans to enforce the new laws. (dpa)