Craig Kauffman's untitled relief slid from its mounting and shattered

A 1967 work of painted plexiglass by Californian artist Craig Kauffman fell off the wall and shattered on 16 July.

An untitled sculpture by another Californian artist, Peter Alexander, was knocked over and smashed in March.

"We deeply regret the incidents," the museum said in a statement. "It is extremely rare that such incidents happen at the Pompidou Centre."

The museum stressed it had followed detailed instructions, given by the owners, on how to display the pieces.

Investigation

We are saddened that such a significant work of art in our collection has been destroyed Michael Govan Los Angeles County Museum of Art

The items were part of an exhibition entitled Los Angeles 1955-1985: The Birth of an Art Capital, which closed on 17 July.

The Kauffman piece, valued at around $70,000 (�37,000) was on loan from the Los Angeles County Museum of Art.

"We are saddened that such a significant work of art in our collection has been destroyed," said the museum's chief executive, Michael Govan, in a statement.

"We have informed the artist and are working closely with the Pompidou to investigate the cause of this accident and to recover the market value of the piece through insurance."

Mr Alexander has already received an insurance payment for his artwork, which was on loan from New York's Franklin Parrasch Gallery.

Prior to the Paris exhibition, he had kept the sculpture in his own collection for several years.