A lawsuit over possible ancient Hawaiian burials along the city’s proposed rail transit route could put the brakes on the $5.5 billion project.

The nonprofit, public-interest law firm Native Hawaiian Legal Corp. filed the suit in Circuit Court on Monday on behalf of a native Hawaiian cultural practitioner.

The lawsuit claims the city did not complete — as required by state law — an inventory survey of archaeological sites, including ancient Hawaiian burials, along the rail’s designated 20-mile route before starting the project. It seeks to declare as unacceptable the project’s environmental impact statement, void all state and county permits, and prevent the city from breaking ground until it completes an archaeological inventory and the historic review process.

The Federal Transit Administration cleared the way for the city to begin construction last month when it gave the project its final environmental approval. The city is seeking $1.5 billion in federal funds to pay for the project and hopes to break ground next month.

U.S. Sen. Daniel Inouye has said the state could lose the $1.5 billion it hopes to get from the FTA if it does not begin construction soon.

The city says it has yet to receive a summons or copy of the lawsuit.

However, Honolulu Mayor Peter Carlisle said Monday that he is aware of the allegations and that they are not new issues.

"We’re satisfied that we have followed the law. We’re confident we can successfully address these arguments in court," Carlisle said.

The lawsuit also names as defendants Gov. Neil Abercrombie, the state Department of Land and Natural Resources and its Historic Preservation Division, and the Oahu Island Burial Council.

Abercrombie signed off on the project’s EIS as one of his first official acts as governor in December.

The DLNR is responsible for enforcing state laws designed to protect the state’s cultural and historic resources, including ancient Hawaiian burial sites.

The lawsuit’s plaintiff, Paulette Kaleikini, was the plaintiff in another suit in which the Hawaii Supreme Court ruled last year that native Hawaiians have the right to challenge construction plans that disturb Hawaiian burial sites.