NEW YORK - Florida real estate developer St. Joe Co. is suing Halliburton Co. over the rig explosion that led to the massive oil spill in the Gulf of Mexico.

The developer said late Wednesday that Halliburton, which was responsible for encasing BP PLC's subsea well in cement, ignored safety procedures and didn't properly manage the cementing process. In deepwater drilling, cementing is a critical element in preventing oil and gas from escaping from a well.

"As a result, the cementing failed, allowing oil and gas to escape the well which caused the catastrophic blowout," the developer said.

St. Joe Co. has a huge stake in the livelihood of the Gulf Coast. The company is the Florida panhandle's largest private landowner, with 70 percent of its 577,000 acres within 15 miles of the coast.

The cause of the blowout has not yet officially been determined. Multiple investigations are under way.

Hundreds of lawsuits have been filed against Halliburton, rig operator BP PLC and the rig's owner, Transocean Ltd. St. Joe Co. went after Halliburton first because it was thought to be the quickest way to collect damages and repay shareholders, said William Brewer, a partner at Bickel & Brewer and lead counsel for the developer.

The company also plans to sue the other companies involved.

A month after the spill, a commercial airport opened on land St. Joe Co. donated, and the company courted Southwest Airlines and Delta Air Lines to fly there. St. Joe Co. is responsible for Southwest's fuel bill if it doesn't book a certain number of passengers in its first two years.

Since the rig explosion April 20, St. Joe representatives say, the value of its properties has declined substantially. Its stock has declined 23 percent; at one point, it had dropped 40 percent. At its worst point, the company lost about $1.4 billion in market capitalization.

Halliburton, based in Houston, said in a statement that "allegations in this lawsuit appear to be without merit and we will vigorously contest it in court." It has said previously that it followed accepted industry practice in cementing the well.

Early Thursday, St. Joe Co. posted a second-quarter loss of $8.6 million, or 9 cents per share, compared with a loss of $44.8 million, or 49 cents per share, a year earlier. The smaller loss reflected much lower expenses. The company didn't have to reimburse Southwest in the second quarter.