The long-awaited groundbreaking ceremony for a new Islanders arena at Belmont Park is tentatively scheduled to take place Monday afternoon, sources said.

Gov. Andrew M. Cuomo’s office has begun sending out email invitations to local dignitaries inviting them to “please join Governor Cuomo for an announcement” at Belmont racetrack.

A spokesman for Cuomo did not immediately respond to requests for comment on the ceremony.

New York Arena Partners, a partnership among the owners of the Islanders, Mets and arena development company Oak View Group, have already begun construction work on a $1.3 billion plan for a 19,000-seat arena, 250-room hotel and 350,000 square feet of retail.

A spokesman for the Islanders group referred questions to Empire State Development, the state agency that has coordinated the process. An ESD spokesman deferred questions to the governor's office.

The ceremony marks an important step toward the end of the Islanders’ decadeslong search for their own arena. ESD has said pre-construction work began at the site in August after New York Arena Partners gained project approvals from three state agencies. The developers anticipate the arena will cost $955 million and take 26 months to build.

Paul Sapienza, president of the Elmont Chamber of Commerce and owner of Sapienza Bake Shop in Elmont, said he received the email invitation Thursday to the announcement with no additional details. He said he can't attend but will have other chamber members on hand.

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"This is great news," Sapienza said. "This is what we've been hoping for."

Cuomo has been a champion of the project since he announced in December 2017 that the Islanders group won the development rights at Belmont. Cuomo also was involved in the negotiations that led the Islanders to split their schedule between NYCB Live's Nassau Coliseum and Barclays Center until the Belmont arena is scheduled to open in 2021.

NHL commissioner Gary Bettman also is expected to attend, sources said. Bettman told Newsday in July the arena at Belmont will "provide a world-class home for this franchise" and "secures their future today and for the next generation of fans.”

Pat Boyle, a board member of the Elmont Chamber of Commerce, said he received the email invite and plans to be at Belmont Monday. He operates Gateway Youth Outreach, a nonprofit in Elmont that runs various after-school programs. “I’m hoping nothing spoils this," he said, "because I’m really looking forward to the development. I think it will help the community.”

The ceremony comes at a time of tension between the Village of Floral Park and state and county officials over the development. Floral Park filed a lawsuit Sept. 9 in an attempt to stop construction and overturn the approvals because the village does not believe the adverse impacts of the project -- namely traffic -- have been properly mitigated. Mayor Dominick Longobardi on Friday declined to comment about the plans for the groundbreaking ceremony.