A well-known Internet site has agreed to clean up what may have become an on-line red-light district of sorts.

Craigslist says it's going to crack down on ads for prostitution on its Web sites.

It's part of an agreement with attorneys general around the country.

From now on, anyone who posts an "erotic services" ad will have to provide a working phone number, and pay a fee with a valid credit card. Craigslist will then provide that telephone and credit card information to law enforcement if it's subpoenaed.

Craigslist's CEO says the agreement will allow legitimate escort services to keep advertising, while discouraging companies that are conducting illegal business.

Police across the country have been arresting people for using Web sites like Craigslist to advertise sexual services.