A silk-screen studio tool used to produce Andy Warhol's "Flowers" is among nearly two dozen art items snatched from a Detroit business, authorities said.
The FBI has not released to the media the names of the business or its owner, the Detroit Free Press said.
The theft of the collection -- which included drawings, prints and paintings by artists such as Larry Rivers, Francesco Clemente, Philip Taaffe, Peter Schuyff and Joseph Beuys -- took place between April 27-29 in the Corktown section of Detroit.
The works, valued at more than $1 million, were not on display or locked up, the newspaper said.
"Whoever is involved may have planned to or may have already transported (the art) outside state lines or possibly outside the country," FBI spokesman Simon Shaykhet told the Detroit Free Press. "Given the nature of this crime and the value of the artwork stolen, we're alerting anyone in the art industry, as well as local pawn shops and those who shop online, that thieves could use any of those avenues to try and sell the stolen goods."