The captain of an Iranian supertanker at the center of a diplomatic standoff no longer wants to keep command of the ship, which is in need of repairs that could impede its immediate departure from Gibraltar, the sailor's lawyer has said.
Any delay in the Grace 1's departure could provide a window for the US to mount further legal action in Gibraltar seeking to seize the tanker amid a growing confrontation with Tehran.
American authorities announced in Washington that they had obtained a warrant to seize the tanker, although court officials in the British overseas territory said they had not received any claim by the end of the business day on Friday. It was unclear if the US had forwarded the warrant.
The tanker and its 2.1 million tons of Iranian light crude oil remained still in waters off Gibraltar a day after authorities ended its detention for allegedly breaching European Union sanctions on Syria.
The release came over the objections of the United States. The head of the Gibraltar government said Iran had promised him not to deliver the fuel to a sanctioned refinery in Syrian territory, although an Iranian official later disputed that those assurances had been delivered.
Tensions between Iran and the US have escalated since 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.
A lawyer representing three Grace 1 crew members who were released from detention on Thursday, have cast doubt on the vessel's immediate departure.
Richard Wilkinson said that the Indian national who commanded the oil tanker until it was detained in early July had asked his Iranian employers to replace him.
"He 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," Mr Wilkinson said. "But he's a professional skipper and needs to wait for a new crew to do a proper handover."
The tanker had been due for repairs in Gibraltar even before it was seized and its detention impeded the replacement of parts, making the tanker unfit for an immediate long voyage, he added.
Iranian Foreign Ministry Spokesman Abbas Mousavi said that his country had made no commitments to gain the release of its tanker, while the chief minister of Gibraltar, Fabian Picardo, insisted on written assurances were received.
"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," he told the BBC. "It could be today. It could be tomorrow. This is a matter now exclusively for the ship agents and ship owners."
The US government said it had obtained a warrant to seize the tanker, citing violations of American sanctions, as well as money laundering and terrorism statutes.
In court documents unsealed in Washington, the US alleges a complex scheme to unlawfully access the American financial system in order to support shipments to Syria by Iran's Islamic Revolutionary Guard Corps, which has been designated as a foreign terrorist organisation.
The complaint alleges that people associated with the ship provided fraudulent shipping documents had obtained oil and departed from an Iraqi shipping port. The US says the documents were forced to mask the fact that the ship had actually departed from Iran.
A senior administration official said the Justice Department's complaint provides additional details associating the ship with the Islamic Revolutionary Guard Corps and its support for terrorism.
Associated Press contributed to this report.