AT&T says it blocked freewheeling Web site 4chan.org this weekend.
The company says it's not because of content, but rather attack traffic coming from the site.
The Web forums at 4chan are full of explicit images, and the site has been cited as the source of several Internet pranks. When AT&T blocked it Friday for its broadband customers, Twitter users speculated that it was an attempt at censorship.
AT&T Inc. spokesman Michael Coe says the site was blocked to protect customers from a so-called "denial of service" attack, which floods targets with meaningless traffic. He says the attack appeared to come from the address img.4chan.org.
On Sunday, AT&T determined that the attack was over and lifted the block.
A message seeking comment from the site was not immediately answered.