Iran's foreign minister told a New York City audience on Wednesday that Tehran respects freedom of navigation in the Gulf, a day after Iranian patrol boats seized a Danish container ship in one of the world's busiest oil shipping lanes.

"The Persian Gulf is our lifeline ... We will respect international navigation," Foreign Minister Javad Zarif said during a discussion hosted by New York University's Center on International Cooperation and the think tank New America. "For us, freedom of navigation in the Persian Gulf is a must."

Danish shipping company Maersk said the crew of the Maersk Tigris was safe and "in good spirits." Iranian authorities seized the Marshall Islands-flagged vessel in the Strait of Hormuz on Tuesday, spurring the United States to send military vessels to monitor the situation.

State Department spokeswoman Marie Harf said the United States had "full authority and responsibility for security and defense matters" related to the Marshall Islands, including ships flying their flag.

"I do know they've requested assistance for the release, I haven't heard the nature of that request, though," Harf told a daily briefing.

The incident occurred at a critical juncture in U.S.-Iranian relations, which could thaw should a tentative nuclear deal between Tehran and six world powers including Washington be clinched. It also coincides with heightened tension between regional archrivals Iran and Saudi Arabia over the escalating civil war in Yemen, in which they support opposing sides.

The vessel was anchored at 1658 GMT (12:58 p.m. EDT) on Wednesday not far off Iran's mainland and close to the major Iranian port of Bandar Abbas, according to Reuters ship tracking data.

Maersk said in a statement that it was in communication with the Danish Foreign Ministry and trying to ascertain why the Maersk Tigris had been diverted.

Iran's Ports and Maritime Organization said a court had ordered the ship seized after ruling against Maersk Line in a case about debts brought by Pars Talaie, an Iranian company.

Zarif told the audience on Wednesday that Maersk was required to pay damages on the basis of a court order. He said the legal proceedings had been going on for some 14 years.

"Simply, our naval forces implemented the decision of the court," Zarif said in New York, characterizing Maersk's actions as "peculiar."

Tasnim, an Iranian news agency, quoted a Pars Talaie lawyer as saying the debt involved a cargo that Pars Talaie had hired Maersk to take from the Iranian port of Abadan to Dubai more than a decade ago but which never arrived.

The 65,000-tonne ship is managed and crewed by Rickmers Shipmanagement but on hire to Maersk Line, the shipping unit of Maersk, the world's largest container shipping concern.

Maersk said it did not own the ship and that it was trying to establish the facts of any legal case. Rickmers said the Maersk Tigris was owned by a group of private investors.

Maersk said the vessel was confronted in international waters while Rickmers said the incident occurred in a widely recognized international shipping lane.

INTERNATIONAL SHIPPING LANE

"The information we had from the (ship's) master at the time of the approach by the Iranian navy ... was that he was at that particular time ... in an international shipping lane," Rickmers spokesman Cor Radings said.

"It is the Strait of Hormuz, which is literally in Iranian waters. But there is an internationally acknowledged shipping corridor in international waters which is used by commercial shipping."

Radings said there were 24 crew members on the vessel, mostly from Eastern Europe and Asia, although there was also a British national among them. The crew was "in relatively good condition and safe" onboard the vessel, which was not damaged.

"We have now been able to communicate with the vessel, which we were unable to do for quite a long period after she was taken deeper into Iranian waters. We have no official contact with the Iranians so far or any official documentation or notification," he said.

The Danish Foreign Ministry said it was monitoring the situation closely and in contact with Maersk.

Global shipping and logistics agent GAC cautioned vessel owners to stay in close contact with security centers while in the Gulf. "No changes have been made to the recommendations for transiting the area in light of the incident, though vigilance and caution is advised," it said. – Reuters