PORTLAND – The selection of a possible resort casino site in Sanford has fueled questions about the impact that the $650 million development might have on the local real estate market.

The issue of property values emerged when some people who live near the proposed casino said they might move if a resort is built near their homes. But interviews with residents, real estate agents and others suggests that the resort proposal is not yet a dominant concern.

However, a group that opposes the plan says casino development elsewhere has harmed nearby residential property values.

The Penobscot and Passamaquoddy tribes said they have purchased an option on 300 wooded acres as a potential site for a casino and resort that would include an 18-hole golf course.

A spokeswoman for the project said Wednesday that developers would address area homeowners’ concerns by locating the golf course between a residential road and the casino structure, creating a 100-acre buffer.

“People pay a lot of money to live on golf courses,” said Erin Lehane, the project’s campaign manager.

Dennis Bailey, a spokesman for Casinos No!, said real estate values have fallen along major travel routes leading to the Foxwoods and Monhegan Sun casinos in Connecticut, and people have a hard time selling homes.

“That’s what happens when a casino comes in,” Bailey said.

But in a market characterized by low inventories and rising prices, real estate agents say most buyers seem focused on typical home-buying considerations, such as whether they like a house and its proximity to work, rather than speculation about whether a casino will be built nearby.

That pattern is likely to continue, said Mike Dubois of Prudential Prime Properties, Dubois Realty. “If the market stays strong, it won’t hurt at all.”

The real estate market in Sanford, the only York County community to approve the idea of a casino, traditionally has been less active and less expensive than in towns closer to the coast. But in recent years, the rising tide of home prices has washed into Sanford.

Median selling prices for existing family homes have jumped rapidly since 2000, when they stood at $99,500. They rose to $109,900 in 2001, $125,500 in 2002, and now stand at $146,900, according to the Maine State Housing Authority.

The tribes want to build a casino in southern Maine to tap into the Boston-area tourism and gambling market. A referendum question that would pave the way for the project goes to a statewide vote in November.