LOS ANGELES » Simon Property Group Inc. is considering raising its $10 billion buyout offer for rival shopping mall owner General Growth Properties Inc. as early as this week, two people familiar with the matter said yesterday.

Simon sent a letter this week to General Growth, which owns Ala Moana Center, Ward Centers and several other Hawaii properties, saying it anticipates boosting its offer above that of a proposal put forth by General Growth and three of its largest stakeholders, the people said on condition of anonymity because they were not authorized to discuss the matter publicly.

That means a new Simon offer would have to value General Growth above $15 a share. Simon's initial offer valued the Chicago-based company at about $9 a share.

General Growth, the nation's second-largest shopping mall operator, sought shelter from creditors last April. It was the largest real estate bankruptcy in U.S. history.

General Growth also owns Whalers Village in Kaanapali on Maui and Prince Kuhio Plaza in Hilo on the Big Island. It manages or markets Windward Mall, King's Shops at Waikoloa Beach Resort on the Big Island, Queen Kaahumanu Shopping Center on Maui and Kapolei Commons in West Oahu. Simon owns Waikele Premium Outlets in Waipahu.

Despite being in Chapter 11 bankruptcy protection for nearly a year, General Growth finds itself in the unusual position of courting buyout offers that promise to pay off creditors in full and give shareholders a premium for their stock.

Indianapolis-based Simon went public last month with its bid for General Growth, but it was rebuffed.

General Growth is looking for a higher offer and has put forward a plan to exit bankruptcy with an investment from Canadian property manager Brookfield Asset Management Inc.; Fairholme Capital Management, one of its largest unsecured creditors; and Pershing Square Capital Management, one of its largest shareholders.

General Growth is expected to seek approval from the bankruptcy court in coming weeks to designate the Brookfield-Fairholme-Pershing proposal as a “;stalking-horse”; bidder as it solicits other buyout offers. A stalking-horse bid is an initial offer for a bankrupt company's assets.

General Growth also plans to ask the court to approve so-called bid protections that would compensate the investor group should General Growth sell the company to another bidder. The company has previously outlined compensating the stalking-horse bidder with warrants to buy 60 million shares of General Growth at an exercise price of $15 a share.

U.S. Bankruptcy Judge Allan Gropper in New York has tentatively set April 13 to hear the request.

In its letter this week, Simon noted that it will likely not participate in the bidding process beyond that date, should the court approve bid protections and effectively raise the costs to acquire General Growth, the people said.

A Simon spokesman declined to comment Monday.

General Growth spokesman David Keating declined to comment beyond a general company statement: “;Our goal is to maximize value for all stakeholders and we have developed a sound process to enable us to achieve that goal.”;

General Growth shares added 35 cents to $15.10 yesterday. Shares in Simon Property rose $2.30 to $84.18.