Photo: © 2010 AP via AAP/Jacques Brinon

The city's mayor says the alarm system in the wing of the museum has been broken since March, AAP reports.

That allowed a single masked thief to break a lock, smash a window, carefully remove the paintings from their frames and, 15 minutes later, walk out with a $150 million booty.

London's Art Loss Register's Antonia Kimbell has told ABC Radio's AM program the works are likely to be used as collateral in other organized crime activities.

"I don't believe that there is someone sitting in a castle sort of rubbing their hands together hoping for this Matisse to be hung above their fireplace," she said.

She says that while terrorism laws have made it easier for police to keep tabs on the criminal economy, a $100 million piece of art still works as "a down payment for another deal, such as an arms deal or a drugs deal".