PORTSMOUTH, N.H. — The owner of an oil tanker that swung loose into the Piscataqua River earlier this year and made contact with a bridge between New Hampshire and Maine is fighting a lawsuit from the two states.

A Portuguese-flagged vessel called the MV Harbour Feature came loose from its mooring at the New Hampshire state pier on April 1 and drifted toward the Sarah Mildred Long Bridge. It became wedged against the steel structure and remained there for hours while tugboat crews waited for the tides to shift.

An inspection by the N.H. Department of Transportation determined one of the bridge’s concrete piers was damaged in the accident, and some pieces of the steel truss were bent.

The ship’s owner faces potential damages in the amount of more than $2 million if found liable for the damage. The two states filed a lawsuit in April seeking to recoup the cost of bridge repairs. The lawsuit alleges the incident occurred because the crew “failed to properly secure the vessel at her berth,” resulting in the “parting of her mooring lines.”

The damage to the bridge was estimated at $2,474,250, according to the suit. New Hampshire and Maine are seeking a judgment that would force the ship’s owners to pay an amount “reasonably necessary” to cover the repairs, as well as accrued interest, late charges and litigation costs.

The states also asked the court to issue a “maritime arrest” warrant, which would have allowed them to keep the ship in port. To avoid the maritime arrest, the owners of the ship posted a “special bond” in the full amount of the estimated repairs on April 5. They also bound themselves to pay any final judgment that may be rendered against the vessel, up to $2.47 million.

On Tuesday, the ship’s owner, Sechste Nordtank-Hamburg, and its operator, TB Marine Shipmanagement, filed a response to the lawsuit in federal court in New Hampshire. They are denying allegations of negligence and asking a judge to dismiss the suit. They are also asking for money they posted in the form of a special bond to be returned.

Attorneys representing the defendants denied that negligence by the crew led to the ship breaking away from the state pier. They also asserted they do not have sufficient information to determine whether the accident between the ship and the bridge caused “extensive physical damage.”

The aging bridge has long been flagged for repairs. It’s scheduled to be replaced by the end of the decade. The repairs taking place now constitute an “improvement or betterment of the bridge” that entails installing new structures and components in the place of old and depreciated structures, according to the defendants.

The ship’s owner is also arguing the plaintiffs in the lawsuit, Maine and New Hampshire, are “guilty of negligence” to a degree that should bar them from recouping repair costs or reduce the amount of any judgment against it.

For the same reason, the ship’s owner is also asking to be allowed to deduct the cost of repairs to the vessel from any judgment against the ship. The defendants also want to deduct costs incurred while the ship was being held in New Hampshire for more than one week.

The U.S. Coast Guard is continuing to investigate the factors that caused the Harbour Feature to break away from the state pier. Michael K. Brown, lead attorney for the New Hampshire attorney general’s office, said the Coast Guard has rendered some preliminary reports that support the states’ lawsuit.

“There certainly has been progress as we continue that investigation, but it has not concluded,” USCG Lt. Nick Barrow said Tuesday. “Usually these are very involved, as you can imagine.”

Barrow said any final report from the Coast Guard will need to be reviewed and approved by high-level officials before it’s released. In general, such investigations focus on best practices for marine safety, he said.

“It’s certainly been a high priority for local Coast Guard investigators to complete that investigation and get it to the upper echelons of the Coast Guard, of course, understanding the high profile nature of it,” Barrow said.

Attorneys Leonard W. Langer and Michael E. Saucier, of the Portland law firm Thompson & Bowie LLP, are representing the state of Maine. They could not be reached for comment Tuesday.

John R. Bass II, Mark G. Furey and Nicholas Bull — attorneys from the Portland law firm Thompson, Bull, Furey, Bass & MacColl — are representing the ship’s owner, as well as a shipping management company named as a co-defendant in the lawsuit. The men could not be reached for comment Tuesday.

Distributed by MCT Information Services