PITTSBURGH -- The popular Web site Craigslist.com is cracking down on ads that act as fronts for prostitution.

The Web site, which hosts free classified ads, has reached an agreement with 42 states, including Pennsylvania, that requires anyone posting on the site's erotic services section to provide a telephone number. They also must pay a fee with a credit card.

Last week, Pittsburgh police arrested eight women they said were freelancing themselves as prostitutes on Web sites like Craigslist.

Police said the women used a number of high-end hotels in and around the city. Among those nabbed were college students and a housewife.