Priceless.

LONDON (Reuters) - A cleaner at London's Tate Britain modern art gallery threw out a bag of garbage that was part of an artwork because it was thought to be trash, British newspapers reported Friday.

The transparent bag of garbage -- full of newspaper, cardboard and other bits of paper -- formed part of a work by German-born artist Gustav Metzger called "Recreation Of First Public Demonstration Of Auto-Destructive Art." It was on display next to a sheet of nylon that had been spattered with acid, and a metal sculpture on a table when a cleaner tossed it out with the other trash.

A Tate spokesman said the mistake was made the day before the exhibition opened at the end of June, and although the bag was later rescued, it had been damaged and Metzger had to replace it with another one. The newspapers said the spokesman would not reveal how much the bag had cost to replace. "It's now covered over at night so it can't be removed," the spokesman told the Times.