MOHEGAN SUN ON Wednesday joined the city of Revere in suing the Massachusetts Gaming Commission, alleging a host of irregularities with the agency’s choice of Wynn Resorts as the eastern Massachusetts casino licensee.

Most of the allegations have surfaced in one shape or form previously, but Mohegan Sun’s filing adds one new twist. It alleges that Steve Crosby, the chairman of the commission, participated behind the scenes in the selection of Wynn Resorts even though he had officially recused himself from the deliberations after questions were raised about his impartiality. He attended a racing event at Suffolk Downs, a partner of Mohegan Sun in its bid for a Revere casino, and he had a prior relationship with one of the people who owned the property where Wynn wants to build its casino.

Mitchell Etess, the chief executive of Mohegan, said in an interview that the details of Crosby’s involvement with his fellow commissioners would come out in the course of litigation. “He was not completely recused,” Etess said of Crosby. “There were interactions that were taking place.”

Otherwise, the lawsuit generally raises concerns that have been aired in one forum or another previously; that commissioners allowed Steve Wynn to change his casino proposal on the last day of deliberations, that they allowed him to redesign the outside of his hotel (Wynn plans to unveil the new design Thursday), and that Wynn’s purchase of the casino property in Everett benefited individuals with criminal backgrounds.

“Apparently enamored with the person behind the Wynn application, but not the actual project presented in that application, the commission ignored the law and manipulated the application process to grant the license to Wynn notwithstanding several disqualifying components of its application,” the lawsuit states.

It’s unclear whether Mohegan Sun has the legal standing to sue the commission. One section of the state gaming law says “the commission shall have full discretion as to whether to issue a license. Applicants shall have no legal right or privilege to a gaming license and shall not be entitled to any further review if denied by the commission.”

Etess said he was not aware of any prohibition on filing a lawsuit. He said Mohegan Sun has lost out in casino license competitions before, but this is the first time the company has filed a lawsuit because the irregularities in this case were just too great. “It’s such a blatant disregard of the statute, it’s amazing,” he said. “They got enchanted with Steve Wynn.”

In addition to the lawsuit brought by Revere, which Mohegan Sun joined as an intervenor, the Gaming Commission is also being sued by Boston and Somerville for its award of the Wynn license.

The Gaming Commission issued a statement Wednesday saying the eastern Massachusetts casino license award was based solely on merit. “As we have stated previously, the commission anticipated that applicants and other invested parties, who are unsuccessful in their bid for one of the limited number of highly-coveted expanded gaming licenses, are going to be intensely disappointed,” the statement said.

Mohegan Sun, best known for its Uncasville, Connecticut, casino, spent more than $40 million trying to win a Massachusetts casino license and came away with nothing. Etess said the experience has made the company reevaluate its growth strategy and shift more toward casino acquisitions and away from high-stakes casino competitions. He said his company is not interested in bidding on the southeastern Massachusetts casino license.

Bruce Mohl oversees the production of content and edits reports, along with carrying out his own reporting with a particular focus on transportation, energy, and climate issues. He previously worked...