General Growth Properties may be prejudiced in favor of a risky bid from Brookfield Asset Management Inc. because of that company’s agreement with William Ackman’s Pershing Square Capital Management, creditors said in court documents.

The bankrupt owner of more than 200 US malls from Boston to Los Angeles, which also had an unsolicited $10bn offer from Simon Property, shouldn’t be allowed to control its bankruptcy for six more months, unsecured creditors said in papers filed yesterday in US Bankruptcy Court in Manhattan.

Creditors added reasons to their prior objection, citing a 24 Feb agreement between Pershing and Brookfield and a “risky” buyout plan. Simon also filed a new objection yesterday, citing that deal. Under General Growth’s plan, Brookfield would be the so-called stalking horse bidder to compete with other potential buyers.