AUGUSTA — Lawyers for the state are reviewing an agreement with a Massachusetts rail company that is expected to restore freight service to Maine’s midcoast region later this year, a transportation official said Monday.

The freight operator, which will be incorporated in the state as Maine Coast Railroad Corp., and Maine’s Department of Transportation are also looking into the possibility of providing passenger service along the long-idle line as a way to ease traffic congestion.

The department’s agreement with Massachusetts Central Railroad Corp. of Palmer to provide freight service “should be back this week,” said Michael J. Murray, director of the DOT’s Rail Transportation Division. “We will be sitting down to dot the i’s and cross the t’s very shortly.”

The agreement would restore service along 52 miles of track, formerly owned by Maine Central Railroad, between Rockland and Brunswick. The state-owned line has been without freight service since 1985, said Murray.

As soon as a lease with the Massachusetts company is executed, plans will be outlined for rehabilitation of the tracks and railbed. That work could last three or four months, said Murray.

“We feel there’s enough existing business and potential business to get us through the first year,” said the Massachusetts company’s president, Robert Bentley. “We’re very comfortable with the situation in Maine.”

The passenger service is envisioned as an alternative for many employees of Bath Iron Works, the region’s largest employer, who ride buses that take them between work and “park and ride” satellite lots dotting the area.

Bentley said his company is looking into setting up a park and ride site north of BIW, and one south of the shipyard.

Meanwhile, state transportation officials are discussing with the Massachusetts Bay Transit Authority the possible purchase of MBTA rail cars that would be run along the Rockland-Brunswick line, said Murray. If it acquired the cars, the state would lease them to Maine Coast Railroad or a subsidiary, said Murray.