DETROIT -

An art market advisory company says treasures in Detroit's art museum eyed for sale by some creditors in the city's bankruptcy could be worth $4.6 billion, but likely would fetch much less at auction.

Artvest Partners LLC also says a forced liquidation of 60,377 pieces in the Detroit Institute of Arts could bring in closer to $1.1 billion.

The report was commissioned by the city and the museum as ammunition against some creditors in Detroit's upcoming bankruptcy trial. It also is broader than an earlier appraisal that placed the value of 2,800 city-owned pieces at between $454 million and $867 million.

The state, private foundations and Detroit automakers have promised more than $800 million to bolster threatened retiree pensions while staving off a sale of the art.

"I think the damage a forced sale would do to our city is much, much greater than trying to work out other options for Detroit's bankruptcy," said AnnMarie Erickson, the DIA's chief operating officer. "There's also the attorney general's opinion that says every work in this building is held in charitable trust."

Detroit Emergency Manager Kevyn Orr's office released a statement which, in part, reads:

"The report makes it abundantly clear that selling art to settle debt will not generate the kind of revenue the city's creditors claim."