The online classifieds website Craigslist has dropped its "erotic services" ads following a high-profile murder in which police say that the killer used the website to find his victim.

Craigslist bowed to pressure from law enforcement authorities in the United States and said it would replace it with an "adult services" section where the posts would be vetted by employees.

Craigslist, the world's largest classified advertising site operating in more than 50 countries, said in a post on the company blog that it was shutting down erotic services even though "the use of Craigslist classifieds is associated with far lower rates of violent crime than print classifieds".

"As of today for all US Craigslist sites, postings to the erotic services category will no longer be accepted, and in seven days the category will be removed," the San Francisco-based company said.

"Also effective today for all US sites, a new category entitled adult services will be opened for postings by legal adult service providers," it added.

Craigslist said postings to the new adult services category will be "manually reviewed before appearing on the site, to ensure compliance with Craigslist posting guidelines and terms of use."

It said new postings will cost $US10, double the cost for postings to erotic services.

"We are optimistic that the new balance struck today will be an acceptable compromise," Craigslist said.

Craiglist has been under pressure for months from state law enforcement officials to drop its section which a state attorney general on Wednesday described as "nothing more than an internet brothel."

The pressure intensified with the arrest of a medical student charged with killing a woman who had posted an ad on Craigslist.

Philip Markoff, 22, has been charged with the murder of Julissa Brisman, 26, who offered massage services on Craigslist and was found shot dead on April 14 in a room at the Boston Marriott hotel.

Markoff is also a suspect in the case of a 29-year-old woman who advertised on Craigslist as an exotic dancer. She was robbed of her credit card and $US800 cash on April 10 from a room at a different hotel.

The case stirred a media frenzy in Boston amid the hunt for a so-called "Craigslist Killer".

Craigslist, which donated all of the profits from erotic services ads to charity, has insisted repeatedly that the site is relatively safe. It said that community moderation "as exemplified by our flagging system" was the best system for policing inappropriate activity.

"Unsurprisingly, but completely contrary to some of the sensationalist journalism we've seen these past few weeks, the record is clear that use of Craigslist classifieds is associated with far lower rates of violent crime than print classifieds," it said.

Illinois Attorney General Lisa Madigan, who was one of several state law enforcement officials pressuring Craigslist to shut down the erotic services category, said she was encouraged by the announcement.

"It's clear to everyone that Craigslist's erotic services section was nothing more than an internet brothel," she said in a statement.

Ms Madigan was one of three US attorneys general who met with Craigslist representatives this month to discuss their concerns that the free online classified service is being used to advertise prostitution.