Have you ever seen the erotic ads on craigslist? It's pretty nast.

COLUMBIA, S.C. – Craigslist's chief executive is suing South Carolina's attorney general, claiming the prosecutor's threat to file prostitution charges against the San Francisco company is unreasonable.

CEO Jim Buckmaster says on his blog he wants a restraining order to keep Attorney General Henry McMaster from pursuing criminal charges.

McMaster said last week he would prosecute Craigslist executives for aiding and abetting prostitution if an ad on the site leads to a prostitution case in South Carolina. McMaster has said his office is investigating, but no charges have been brought.

In a statement, McMaster says the lawsuit shows Craigslist is taking his investigation seriously and called it a victory. The lawsuit was filed late Tuesday night in a federal court in South Carolina