Maersk Line, the Danish shipper that chartered a Marshall Islands-flagged cargo vessel which Iranian forces have captured, said the reason for stopping the ship could be related to a 2005 cargo case.

Maersk Line spokesman Michael Storgaard said the company learned Thursday that an Iranian appeals court had ruled Maersk must pay $3.6 million for a 10-container cargo delivered a decade ago on behalf of an Iranian company in Dubai, United Arab Emirates. However, the cargo never was collected, according to Storgaard, adding it eventually was disposed of by local authorities.

Maersk Line said the Iranian company took the issue to the Tehran Revolutionary Prosecutor's Office and claimed recovery of $4 million as the value of the cargo, but it challenged the lawsuit successfully and, in 2007, the case was dismissed.

The Iranian company later initiated civil proceedings against Maersk Line in Tehran Public Civil Court, and on Feb. 18, 2015, after four years of proceedings, the court ordered the Danish shipper to pay the Iranian company $163,000.

“We have accepted the ruling and are willing to pay in accordance with same,” Maersk Line said in a statement.

But then on Thursday, the Danish shipper said it learned that the Iranian company appealed the case, seeking a higher compensation, and an appeals court ruled that Maersk Line has to pay it $3.6 million instead of $163,000.

“As we do not have the details of the ruling, we are not able to comment hereon, nor at this point speculate on our options,” Maersk Line said.

“Our paramount concern remains the safety of the crew and the safe release of the vessel. We will continue to do everything we can to resolve this matter with the relevant Iranian authorities.”

Storgaard told The Associated Press that the ship and crew aren't theirs. MV Maersk Tigris, operated by Rickmers Ship Management in Singapore, was boarded on Tuesday.

Cors Radings, a spokesman for Rickmers, told Fox News that as of Thursday, there has been no change in the status of the ship and her crew, and that the company has not spoken with the crew in the past 24 hours.

The ship remains anchored south of Bandar Abbas off the coast of Qeshm Island outside the Strait of Hormuz, according to MarineTraffic.com, which tracks merchant vessels.

On Wednesday, Radings said the Maersk Tigris crew remained confined to their cabins and mess decks enforced by Iranian guards on board.  The crew is only allowed to move about for head calls.

"We are seeking advice from international parties able to assist us," Radings said. He declined to comment on who was taking the lead in the talks with Iran over the ship's fate. Pentagon officials point to the government of Denmark.  

The Pentagon said Wednesday that the U.S. would "be able to respond" if necessary to help a Marshall Islands-flagged ship that was diverted, and boarded, a day earlier by Iran -- though it remains unclear how far the U.S. Navy might be willing to go if the tense situation escalates.

Fox News’ Lucas Tomlinson and The Associated Press contributed to this report.