A hard rock band has billed the U.S. government for "musical services" after learning that their songs were used during interrogations of prisonersat Guantanamo Bay.

Canadian rock/industrial band known as Skinny Puppy reportedly heard from a fan and former Gitmo prison guard that their music had been used as a form of torture at the military base in Cuba, reports ABS News.

While the band chose to bill the U.S. government for a "random evil figure" of $666,000 as compensation for the unauthorized use of their music, they don't actually expect to get a response.

A military spokesman told ABC News the Department of Defense has not received an invoice and is committed to the humane treatment of detainees.

The band says they have been made aware that four different songs of theirs had been used on at least four occasions to "inflict damage" on suspected terrorists in the prison.