The FBI has been drafted by "The Avengers" actress to investigate, according to celebrity news website TMZ. An FBI spokesman declined to confirm or deny the investigation, and a representative for Johansson was not immediately available to comment.
The photos show the 26 year-old actress in a towel with an exposed backside, while another shows her topless. They were posted on several celebrity gossip websites.
Johansson's nude pictures are the latest to hit the Internet after actresses including Jessica Alba and Vanessa Hudgens also suffered the embarrassment of explicit photos appearing on the Web.