Pembroke Pines and Southwest Ranches likely are headed to state court after a final mediation session Tuesday failed to resolve differences between the municipalities arising from a canceled federal detention center once proposed for Southwest Ranches but vehemently opposed by neighboring Pembroke Pines.

Attorneys and administrators representing the two Southwest Broward municipalities failed to agree on one of the most basic issues — whether two contracts between them had been breached — and perhaps the biggest question of all: Is Pembroke Pines financially liable for the decision by U.S. Immigration and Customs Enforcement to abandon plans for a proposed detention center in Southwest Ranches?

Jeff Nelson, mayor of Southwest Ranches and the only elected official in attendance at Tuesday’s mediation, said Pembroke Pines is to blame for ICE’s decision because the city interfered with the project and refused to approve a water and sewer services application filed by Corrections Corporation of America, the private prison contractor that owns the land where the detention center would have been built.

“It means a lot to the town,’’ Nelson said of the canceled project. “It hurt us tremendously. And we want to hold them accountable.’’

Nelson said Southwest Ranches would have received about $2 million a year from the facility, and he wants at least that much from Pembroke Pines.

Sam Goren, city attorney for Pembroke Pines, said ICE reached its decision independent of the city’s actions. Pembroke Pines has refused to accept any financial liability for the canceled project.

Goren said Pembroke Pines was prepared to process CCA’s water and sewer application, but that the company had failed to provide additional information requested about the project.

“The city is not sure exactly what it is we’re arguing about,’’ Goren said.

Last summer, ICE tentatively selected Southwest Ranches as a finalist for a new immigrant detention center, one of the largest in the nation. Residents protested. By December, Pembroke Pines commissioners began to cancel previously-approved agreements between the municipalities — in an effort, Southwest Ranches officials say, to stop the proposed detention center.

Keith Poliakoff√, town attorney for Southwest Ranches, said the town likely will sue Pembroke Pines for breach of contract for cancelling two specific agreements.

The first contract dated to 2005, and largely concerned the closure of roadways shared by residents of both municipalities west of Interstate 75. The agreement also contained a clause that Pembroke Pines officials would not “interfere” with efforts to bring a prison or detention center to CCA’s property, which is roughly 25 acres and sits between U.S. 27 and I-75 between Sheridan Street and Stirling Road.

CCA bought the property in 1997 with the expectation that the company would build a prison there, Poliakoff said. The property is zoned for such a use, and Pembroke Pines officials knew a prison or detention center would be built there because the city required the property owner to install infrastructure for delivering water and sewer to the site before it was incorporated into Southwest Ranches in 2000.

Pembroke Pines officials canceled the 2005 roadways agreement in December 2011, and soon after, city commissioners signed a letter to President Barack Obama asking him to intervene in the project.

The second agreement in question was unanimously approved by Pembroke Pines commissioners in June 2011, and related to the city’s delivery of fire, emergency medical, water and sewer services to Southwest Ranches and the proposed facility. Pembroke Pines would have received a one-time $3 million payment from CCA for hooking up water and sewer service under that agreement, plus annual fees of about $2 million for providing, water, sewer fees, fire and emergency medical services.

But Pembroke Pines commissioners voted to cancel that contract during a March meeting, following prolonged and vociferous protests from residents.

At the same meeting, Pembroke Pines commissioners also voted to sue CCA in state court to seek a declaratory judgment regarding the city’s legal requirement to provide water and sewer outside its boundaries.

The next morning, before Pembroke Pines filed its lawsuit, CCA pre-empted the city’s actions by filing for a declaratory judgment in federal court. CCA also is asking for financial damages from Pembroke Pines, said Leonard Samuels, an attorney representing the company and who attended Tuesday’s mediation.

The federal lawsuit took precedence over the state court action, and is still pending.

Southwest Ranches and CCA have worked together since about 2000 to bring the facility to fruition, Nelson said. CCA and Southwest Ranches agreed that the company would pay the town 4 percent of the daily $75 fee CCA would have received for each inmate detained at the facility, which would have had 1,500 beds.

Annually, that would have amounted to about $1.6 million from CCA, Poliakoff said. Southwest Ranches also would have received an estimated $350,000 a year in property taxes from the project, he said.

CCA’s attorney, Samuels, said Pembroke Pines’ actions have “totally devalued our property.’’

H. Mark Purdy, a retired circuit court judge acting as mediator, cautioned both parties that failure to reach an agreement in mediation would be costly and time-consuming.

“It would be difficult for the public to endure that,’’ Purdy said.