The state Gaming Control Board issued regulations this month which mean anyone who owns a license for a slot machine casino in the state will be able to hold an interest of as much as one-third in any or all of the other 13 casinos in the state.

The ruling by the board is good news for Harrah's Entertainment Inc. The decision clears the way for the gambling powerhouse to own part of a proposed casino at Station Square while keeping a 50 percent interest in and being licensed to operate a proposed racetrack and slots parlor being built in Chester, Delaware County.

But Harrah's isn't the only one affected. The regulation opens the door for other gambling companies and investors to own up to a third of every other slot machine casino in the state.

The Nov. 17 decision by the state Gaming Control Board appears to be in keeping with the intent of the state law legalizing slots gambling, which contained a provision allowing an operator of one casino to own up to a third of every other.

The ruling doesn't sit well with some.

The Pennsylvania Thoroughbred Horsemen's Association fears the regulation will open the door for one company to monopolize the state slots gambling industry and will funnel business away from the seven racetrack casinos. It said the regulation could detract from a primary purpose of the slots act, which was to boost the horse racing industry in the state.

The association had argued to the board that racetrack casino licensees should be prohibited from owning any part of any of the five standalone slots casinos or two resort casinos to be built in Pennsylvania. The state's gambling law says applicants for casinos at racetracks may not also apply for stand-alone or resort casino licenses. They may, however, hold an interest in those casinos.

"Clearly, the intent of the Gaming Act is to preclude ownership of multiple categories of slot machine licenses and to encourage a healthy competitive environment in the gaming industry in Pennsylvania, rather than establishing regulations that allow for the creation of a monopoly by a few licensed entities," Salvatore M. DeBunda, counsel for the association, wrote in a letter to the board.

The board rejected the association's interpretation.

In terms of local impact, the regulation would allow Harrah's to own up to a third of the proposed casino at Station Square, where it expects to partner with Forest City Enterprises, to compete for the Pittsburgh license.

Harrah's sold most of the complex to the Cleveland developer in 1998 but retained an option to build a casino there through 2007. The option would allow it to develop a casino on land east or west of the Sheraton Station Square Hotel.

In Pittsburgh, the regulation also has implications for MTR Gaming, which is expected to be licensed to operate a racetrack casino in Erie. It also is proposing to build a stand-alone casino on the North Shore near the 16th Street Bridge. It will now be able to own up to one-third of that venue should it win the license.

A spokesman previously said MTR would put together a team to apply for the casino license and manage the venue if one is awarded.

Joseph Weinert, vice president of Spectrum Gaming Group, an industry consultant, said the new regulation favors companies such as Harrah's.

"That's good news for operators that seek to have a broader geographic distribution of their product, notably Harrah's Entertainment, which has a vast network of gamblers that it uses to ultimately try to direct gamblers to marquee properties in Las Vegas and Atlantic City," he said.

Not surprisingly, Harrah's lauded the board for permitting multiple ownership.

In a letter to the board, Mark Aronchick, attorney for Harrah's operating subsidiaries, said members had "correctly interpreted" the intent of state law.

He maintained the state General Assembly had given the board broad discretion over such matters "to best ensure that licenses are held by those persons who have the ability and experience to make Pennsylvania's nascent gaming industry a success and maximize revenues for the commonwealth while maintaining reasonable restrictions on the control of multiple licensed gaming facilities and safeguarding the industry's integrity."

The Thoroughbred Horsemen's Association, a nonprofit corporation made up of about 4,000 thoroughbred horse owners and trainers, is worried that racetrack casino operators who also own part of bigger stand-alone casinos will try to direct customers, particularly high rollers, to the larger venues. That, it said, could cut into revenues available to the horse racing industry.

The reason is that, under the slots law, a portion of the revenue generated by each of the seven racetrack casinos will go into a fund for the benefit of horse owners, trainers and the industry as a whole in Pennsylvania.

If owners of multiple casinos divert customers from the horse-racing venues, it would affect the size of the pot available to horsemen, Mr. DeBunda said.

"It certainly creates the opportunity for [horse-racing industry revenues to be affected] and I don't think the Legislature intended that to be the case," he said in an interview.

While the association is concerned that the new regulation creates the potential for a company to monopolize the Pennsylvania casino market, Mr. Weinert doesn't see that happening.

He said there were too many players jockeying for a piece of the action. He said Las Vegas Sands Inc. and Aztar Corp., the owner of the Tropicana casinos in Las Vegas and Atlantic City, N.J., were competing for a stand-alone casino license in the Lehigh Valley.

MTR is one of at least five potential competitors for the Pittsburgh license. At least two others, the Penguins and Alco Parking Corp. President Merrill Stabile, also are expected to have partnerships with national gambling operators.

Donald Trump and Planet Hollywood are competing for one of the two casino licenses available in Philadelphia, Mr. Weinert said.

"I think there's going to be a good diversity in Pennsylvania, which is helpful for the industry," he said.

While Mr. Weinert believes Harrah's will explore "multiple options" in Pennsylvania, he said those options appeared to be limited, given the number of other gambling companies interested in the market.

"I don't see [Harrah's] dominating the Pennsylvania gaming industry," he said.