LAS VEGAS - Hackers bent on derailing Anonymous clashed with members of the notorious group at a DefCon gathering in Las Vegas late Saturday.

"Hubris" and "Asherah" of startup Backtrace Security condemned Anonymous for "bully behavior" and argued that the group was trying to pass of reckless opportunism as Internet-age activism.

"When Anonymous started it was a good idea," Asherah said during what exploded into the fieriest session yet at the infamous DefCon hacker get-together.

"Now, it is in violent freefall," she continued as the audience divided into opposing camps of hackers cheering in agreement and angry Anonymous fans heckling and shouting.

"We are trying to derail something that has gone wrong very quickly and is going to get worse."

Asherah presented a history of Anonymous, saying the same people were behind splinter hacker group Lulz Security.

The speakers laughed, cursed, and openly taunted Anonymous while telling of how they were able to identify some members of the group because they used their hacker names at other online venues such as Facebook and Yelp.

Backtrace told of luring Anonymous members into online video chats, capturing images of their faces and getting them to openly talk about illegal antics they have done and with whom.

The session turned into a shouting match when representatives of Anonymous interrupted from the audience and then joined Hubris and Asherah on stage to field questions.

"I believe what (Anonymous is) doing is for the good of everyone," said an Anonymous member with a mask similar to the one worn by the protagonist in the film "V is for Vendetta," sparking applause from one side of the large room.