Armand Hammer Is Sued by His Late Wife’s Sole Heir : Art: An 18-count fraud suit claims at least a half-interest in the Occidental Petroleum Corp. chairman’s famed collection.

The sole heir of the late wife of Occidental Petroleum Corp. Chairman Armand Hammer filed an 18-count fraud suit Wednesday, claiming at least a half-interest in Hammer’s famed art collection--the central element of a controversial museum now under construction in Westwood.

The court action, filed in Los Angeles County Superior Court, named as defendants Hammer and Occidental, as well as the privately chartered Armand Hammer Foundation and the Armand Hammer Museum of Art and Cultural Center. A Chicago law firm--Lewis, Overbeck & Furman--and two partners in the firm, David J. Creagan Jr. and John R. Burdick Jr., were also named as defendants in the complaint, which alleged fraud, legal malpractice and financial misconduct in seeking damages of at least $700 million.

The lawsuit was filed by Robert Weiss, executor of the estate of Francis Hammer, who died in December after 33 years of marriage to Armand Hammer. Weiss is the husband of Joan Weiss, a niece of Frances Hammer who is, under the terms of a will filed in January of this year, her only heir. The Weisses reside in Los Angeles.

The Hammer museum, which is due to open in November at the corner of Wilshire and Westwood boulevards, is already embroiled in three separate lawsuits filed by Occidental shareholders who seek a court order halting Occidental’s involvement in the project as well as money damages.

In a Delaware suit, dissident shareholders seek to derail a proposed settlement of the museum dispute. In April, the Weisses sent a letter to the Delaware judge suggesting that any claim they might make involving ownership of the Hammer collection could affect the museum project.

Any serious dispute over ownership of artworks to be displayed at the Hammer museum would raise new questions about the controversial art center’s viability.

In addition to challenging the ownership of Armand Hammer’s art collection--a group of several hundred works that has been exhibited around the world and is valued at as much as $450 million--the Weiss lawsuit alleged that Frances Hammer was fraudulently deprived of ownership interests in thousands of shares of Occidental stock and millions of dollars in cash paid to Armand Hammer in salary and as fringe benefits.

The suit alleged that Hammer, his attorneys and Occidental officials deceived Frances Hammer about her ownership rights to Hammer’s assets, effectively depriving her heir of her inheritance.

The lawyers named as defendants could not be reached for comment Wednesday.

Howard Collins, an Occidental Petroleum press spokesman who customarily represents Hammer, his foundation and the museum as well as Occidental--declined to comment on the lawsuit. Earlier, however, Occidental produced photocopies of three documents signed by Frances Hammer in 1983 and 1989 in which she apparently waived her interest in Armand Hammer’s art collection and other community property.

In the Wednesday court filing, however, Richard C. Cleary, a lawyer for the Weisses, attacked the documents as part of a “pattern of fraud and deceit� in a “scheme� by Armand Hammer that relied on “oppressive, fraudulent and malicious� tactics.

Occidental Petroleum is spending about $136 million to construct and initially endow the museum.