The operator of a cargo ship boarded by Iranian forces as it was traversing the Strait of Hormuz said Wednesday that the crew onboard the ship is safe, but the company is still trying to determine why the ship was seized by Iran.

The Marshall Islands-flagged MV Maresk Tigris was en route Wednesday to Bandar Abbas, the main port for Iran's navy, under escort by Iranian patrol boats, according to Maersk Line, the company that had chartered it.

Iranian Foreign Minister Javad Zarif claimed Wednesday that the ship has a history of legal issues, including failing to pay for damages, but he did not elaborate. The ship was asked to come to port, and when it refused, Iran's navy took action, he said.

Zarif, speaking at an event at New York University, also said “freedom of navigation in the Persian Gulf is a must and must be defended.”

Iran's semi-official Fars news agency Wednesday quoted the maritime deputy director of Iran's Ports and Sailing Organization, Hadi Haghshenas, as saying the ship was seized over “some unpaid debt.”

More On This...

"Maersk Line owes some money to an Iranian company and the court has ruled that Maersk should pay the debt." The report did not elaborate.

Cor Radings, a spokesman for the ship's operator, Rickmers Ship Management in Singapore, said the company had no known issues itself with Iran and that it would be up to Maersk to comment on the Iranian claim.

Maersk Line spokesman Michael Storgaard earlier said his company had not been "able at this point to establish or confirm the reason behind the seizure" and said later he had no new information when asked about the Iranian allegations.

Meanwhile, the Pentagon and State Department offered conflicting statements as to whether the U.S. has a responsibility to protect the ship.

"I am not aware of any specific agreement or treaty that calls for us to protect Marshallese vessels," a defense official told Fox News on Wednesday.

But a day earlier, State Department spokesman Jeff Rathke said otherwise.

“The security compact between the United States and the Republic of the Marshall Islands gives the U.S. authority and responsibility for security and defense matters that relate to the Marshall Islands, including matters related to vessels flying the Marshallese flag,” he said at a briefing.

The Marshall Islands -- officially known as the Republic of the Marshall Islands, and a former U.S. trust -- enjoys "associated state" status with the United States, meaning the U.S. agrees to defend the islands, provide economic subsidies and access to federally-funded social services. The islands have little natural resources, therefore in recent years have focused on expanding its service economy -- including delving into the shipping industry.

Radings said the company had been in touch by phone with the crew earlier Wednesday.

"We have been in contact with the crew in the last few hours and have received confirmation that they are safe and in a relatively good condition," Radings said.

Radings told Fox News the 24-man crew remains mostly confined to their cabins, except for head calls and trips to fetch their meals.  

The spokesman said the ship is only carrying "general cargo" on a normal route and does not know why she was detained. The ship had no "special cargo" such as military equipment, Radings said.

Radings said his company has not been in direct contact with the Iranians. When asked if he had been in contact with the U.S. Navy or other government officials outside the distress call yesterday, he replied vaguely "we are seeking advice from international authorities."

Iranian forces boarded the MV Maresk Tigris on Tuesday after firing warning shots across the bridge, prompting the U.S. Navy to dispatch a destroyer and a plane to the area in response.

Radings confirmed reports that there were no Americans on board, identifying the 24 people crew members as "mainly from Eastern Europe and Asia." He said the ship was owned by "private investors" but would not elaborate.

A spokesman for the U.S. Navy 's 5th Fleet responsible for the Persian Gulf and the Strait of Hormuz told Fox News that the USS Farragut, a guided missile destroyer, continues to "conduct transits" of the Strait of Hormuz and Navy P-3 reconnaissance aircraft continue to fly in the area.  Additionally, there are three U.S. Navy patrol craft near the Strait as well. The U.S. Navy has 10 patrol craft home-ported in Bahrain.

"There are always a line of vessels transiting the Strait, I can't speculate why this vessel was taken," said Cmdr. Kevin Stephens, spokesman for 5th Fleet, when asked why Maersk Tigris was detained by the Iranians.

The U.S., other world powers and Iran are trying to hammer out a final deal over Iran's nuclear program. Last week, the U.S. Navy dispatched an aircraft carrier and guided missile cruiser to the Arabian Sea amid worries that a convoy of Iranian cargo ships was headed to Yemen to deliver arms to the Shiite rebels fighting to take over Yemen.

In Tuesday's incident, the intercepted ship was traveling through the narrow Strait, which is technically Iranian and Omani territorial waters, but under international agreement is open to foreign ships making an innocent passage, according to the Pentagon.

It wasn't clear whether the ship had strayed off course into coastal waters not protected by that agreement.

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