HONG KONG -- A family feud roiling one of the world's largest property developers took a fresh turn Thursday when the company's chairman and chief executive won a temporary injunction fending off what he called an attempt by his two younger brothers to oust him.

Walter Kwok, the embattled head of Hong Kong-listed Sun Hung Kai Properties Ltd., has been on a three-month leave since a dispute erupted with his brothers Thomas and Raymond, both vice chairmen and managing directors. The dispute, which is only now being spun out in public view, casts a pall over the company's vaunted name.

With a market capitalization of about US$45 billion, Sun Hung Kai is the biggest listed real-estate company, according to Thomson Reuters. It develops residential property and high-end offices in Hong Kong and is the developer of Hong Kong's three tallest skyscrapers, including the International Commerce Center, which will be the world's third-tallest building when completed in 2010. The three brothers control about 42% of the company through a trust, making them the 23rd-richest billionaires, according to Forbes magazine.

For decades, the company has maintained a reputation for unity, dependability and quiet professionalism. The three brothers were known for their ability to work together since the death in 1990 of their father, who helped found Sun Hung Kai in 1963.

According to a complaint Mr. Kwok filed with Hong Kong's high court Thursday, his brothers this year mounted a months-long campaign to push him out, armed with medical reports diagnosing the 58-year-old Mr. Kwok as bipolar, reports Mr. Kwok says were based on misinformation his brothers gave a doctor. Bipolar disorder, or manic depression, causes extreme mood swings.

The brothers tried to relegate Mr. Kwok to the role of nonexecutive director and install their octogenarian mother, Kwong Siu-hing, as chairman, according to the complaint. Mr. Kwok won a reprieve from Hong Kong's high court just an hour before a Sun Hung Kai board meeting at which he says his brothers were planning to seek his ouster. Ms. Kwong is a major shareholder in the company and is said to exert a great deal of power despite holding no formal position. She couldn't be reached to comment.

"I didn't think it was going to get this messy," a longtime friend of the family says. "They had really done a great job of running the company as three brothers, and there was an absolutely seamless transition when their father died, so this is really quite disturbing."

The dispute comes as Sun Hung Kai pushes a major expansion in mainland China, where it has a relatively small presence compared with its peers, and continues work on the International Commerce Center. In his complaint, Mr. Kwok catalogs a series of business disagreements between him and his two brothers, including disputes over the leasing of the ICC and the acquisition of a parcel of land in Hong Kong at what Mr. Kwok says was an inflated price.

Sun Hung Kai confirmed the court approved a temporary injunction but said the injunction "absolutely does not mean that the court had made a final ruling," noting a separate session would be required to establish any grounds for argument. A spokesman for Sun Hung Kai says that the company is seeking legal counsel and that Mr. Kwok will continue his leave of absence. The company's development and operations, the spokesman says, will be "business as usual." Mr. Kwok couldn't be reached to comment.

Reaction in the market was muted because results of the board meeting weren't known until after the close Thursday. Shares in Sun Hung Kai fell HK$1.30 (16.7 U.S. cents) to close at HK$136.10, ahead of the meeting.

Write to Jonathan Cheng at jonathan.cheng@wsj.com

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