NEW YORK—A New York art gallery is suing Enron Corp.'s former chief operating officer of global markets, Jeff Shankman, for allegedly trying to extort more than $150,000 by claiming a painting he bought was a forgery, Bloomberg reports.

Shankman purchased three artworks from Historical Design, Inc. in November 1997 for $40,000. He complained this year that one was a fake, according to the gallery. He said he would "go public" with accusations that a gouache painting, Les Visiteurs, signed by J. Lambert-Rucki, was a forgery unless he was paid at least $150,000, according to court papers.

Historical Design says the painting is authentic, and it is seeking $400,000 in damages and other fees. The gallery also claims the artwork belongs to Enron's creditors and shareholders, not Shankman.

"Shankman, a former high-echelon Enron executive and art dealer, maliciously formulated and carried out a fraudulent plan or scheme seeking to extort cash from the plaintiff," Historical Design said in a complaint filed Oct. 7 in New York State Supreme Court in Manhattan.