BOSTON (AP) – A Massachusetts Indian tribe unveiled new details Thursday of a proposed $500 million resort casino, while a second tribe threatened court action over the state’s contention that it disqualified itself from gambling in a 1980s land settlement.

The new state gambling law that allows for up to three resort casinos gives exclusive rights to a federally-recognized Indian tribe to develop a casino in southeastern Massachusetts if it can negotiate a compact with the state by July 31.

The Mashpee Wampanoag Tribe and the Martha’s Vineyard-based Wampanoag Tribe of Aquinnah have both secured options to purchase land for a casino in the region, but only the Mashpee – which detailed its proposal on Thursday – has begun compact talks with Gov. Deval Patrick’s administration.

The tribe said it hoped to construct a 150,000-square-foot casino on 146 acres of land at the junction of Routes 24 and 140 in Taunton.

The complex, to be built in stages over a five-year period, would also include three 300-room hotels, retail shops, meeting space for business events and a family-oriented water park.

Tribal chairman Cedric Cromwell said the project would create about 1,000 unionized temporary construction jobs and that once finished, the casino would employ more than 2,500 people with an $80 million annual payroll.

“The jobs and direct economic impact from this project will have a meaningful positive effect on thousands of local families,” said Cromwell.

The project has the support of Taunton Mayor Thomas Hoye Jr. and other city officials, who are currently negotiating a host community agreement with the tribe. The plan must also get the support of city voters.

Meanwhile, the Aquinnah Wampanoag said they remain ready and willing to enter compact negotiations with Massachusetts despite the state’s position that the tribe surrendered gambling rights – either on Martha’s Vineyard or on any future land it acquired in the state – in the 1985 land claims settlement.

Jerome Levine, an attorney with Holland & Knight, a law firm retained by the state to assist it with Indian gambling negotiations, wrote in a letter to the tribe last week that because of that settlement, the firm was not authorized to begin compact talks.

Patrick confirmed that view on Thursday.

“We have been advised that, legally, the Aquinnah have waived their rights to tribal gaming,” Patrick said during his monthly “Ask the Governor” program on WTKK-FM, adding that the tribe could still seek a commercial casino license.

The tribe strongly disputes the state’s position, claiming its right to pursue gambling is protected under the federal Indian Gaming Regulatory Act.

“If the governor refuses to negotiate, (the law) provides for specific remedies that we will pursue in federal court,” tribal chairwoman Cheryl Andrews-Maltais said in a statement.

To support its contention, the tribe has referenced a 1997 letter from the U.S. Department of Interior. The letter, signed by Michael Anderson, then acting assistant secretary for Indian Affairs, concluded that the Aquinnah would be eligible to conduct gambling activities on land in Fall River. The tribe at the time was eyeing a possible casino in that city.

Andrews-Maltais said attorneys representing the tribe and the state had “frank and constructive discussions” at a meeting that followed the letter sent by Levine, and a spokesman for the tribe indicated Thursday that a lawsuit was not imminent.

Patrick reported “good progress” in compact negotiations with the Mashpee Wampanoag. If an agreement is not reached by July 31, the casino law allows for commercial developers to bid for the southeastern Massachusetts license.

Even if the tribe reaches agreements with the state and the city, it would still face other obstacles to building a casino, including a requirement that the land be placed in federal trust.