In a sad case of art imitating life, Second Life has suffered a number of terrorist attacks in its virtual world.

The Second Life Liberation Army, or SLLA, detonated bombs outside a virtual American Apparel store and a Reebok store.

The bombs appear as white balls to block out part of the screen; unlike real world bombs, they don't cause fatal damage.

The SLLA want to replace Linden Lab rule with a democracy so that the four million residents could have a say in what goes on in the virtual world.

"As Linden Lab is functioning as an authoritarian government, the only appropriate response is to fight", the group says on its website.

"When the SLLA succeeds in its aims it will disband and hand power back to the political wing of the movement."

Linden Lab is able to banish avatars or members if they are harassing or somehow interfering with other users' rights to enjoy the world.

The company up until now has viewed the SLLA bombings as a bit of fun.

The SLLA is also demanding that Linden Lab go live on the stock market and offer shares to each user.

"Ultimately, instances in which residents engage in simulated violence will have to be taken on a case-by-case basis", Catherine Smith, Linden Lab marketing director, has said.

"We believe recent events involving SLLA protests lack malicious intent."

"Residents' reaction to such attacks has been decidedly tongue-in-cheek."