The captain of an Iranian supertanker which was seized off Gibraltar no longer wants to be in command of the ship, his lawyer said.

The Grace 1 and its cargo of 2.1 million tonnes of Iranian light crude oil remains shrouded in heavy fog off the British overseas territory a day after authorities lifted a detention order for breaching European Union sanctions.

The United States tried to stop the release but authorities in Gibraltar say they went ahead after Iranian authorities promised not to deliver the fuel to a sanctioned refinery in Syria.

Gibraltar Persian Gulf Tension
The captain of the Grace 1 supertanker wants to be replaced, his lawyer said (Marcos Moreno/AP)

The tanker is in need of repairs that could prevent its immediate departure from Gibraltar.

Richard Wilkinson, a lawyer for the three crew members released from detention on Thursday, said the Indian national who commanded the Grace 1 has asked his Iranian employers to replace him.

Any delay of the vessel’s departure could provide a window of opportunity for the US to mount further legal action and try to stop the tanker amid growing confrontation with Tehran.

Tensions have escalated since President Donald Trump last year unilaterally pulled the US out of the 2015 nuclear deal signed by Iran and other world powers.

The decision re-imposed sanctions on Iran, stopping billions of dollars in business deals, largely halting the sale of Iran’s crude oil internationally and sharply depreciating Iran’s currency, the rial.

More recently, the Persian Gulf has seen attacks on oil tankers and other high-stakes confrontations.

In early July, Tehran seized the British-flagged oil tanker Stena Impero in apparent retaliation for the detention of the Grace 1. Analysts said the release of the Grace 1 by Gibraltar could see the Stena Impero go free.

But that prospect remained up in the air on Friday with Mr Wilkinson casting doubts on the vessel’s immediate departure.

“He (the captain) doesn’t want to stay in command of the ship, he wants to go home, because he wasn’t happy to go back and pick up the broken pieces,” said Mr Wilkinson. “But he’s a professional skipper and needs to wait for a new crew to do a proper handover.”

The lawyer said the tanker had been due for repairs in Gibraltar even before it was seized, which impeded the replacement of certain parts, making the tanker unfit for an immediate long voyage.

Adding to the uncertainty, the next possible destination of the cargo became a point of contention as Iranian and Gibraltar authorities showed disagreement over the terms that led to the ship’s release.

Iranian Foreign Ministry Spokesman Abbas Mousavi on Friday said the country had made no commitments to gain the release of its tanker, while the chief minister of Gibraltar insisted on the written assurances it had received.

The captors of the vessel “raised the issue of commitment in a bid to make up for their humiliation caused by this illegal act and piracy”, Abbas Mousavi said, according to the semi-official Tasnim news agency.

“We announced that Syria was not its destination and we have upheld the same … and reiterated that it was nobody’s business even if it was Syria,” he added.

In response, the Gibraltar government issued a statement saying that “the evidence is clear and the facts speak louder than the self-serving political statements we are hearing today”.

Authorities in the territory at the mouth of the Mediterranean Sea did not reveal if the vessel was expected to leave any time soon. Chief Minister Fabian Picardo said it was now strictly a matter for the ship’s agents and owners.

“She is able to leave as soon as she organises the logistics necessary in order to sail a ship of that size wherever it is going next,” Fabian Picardo said. “It could be today. It could be tomorrow. This is a matter now exclusively for the ship agents and ship owners.”