Men who boarded and seized a ship in the Gulf of Oman have left the vessel and all those remaining on board are safe, officials say.
A UK maritime security agency said the potential hijacking of the Panama-flagged MV Asphalt Princess had ended but gave no further details.
The bitumen tanker was seized on Tuesday heading into the congested approach to the Strait of Hormuz.
It is not clear who seized the ship, but analysts suspected Iranian forces.
Iran’s Revolutionary Guards dismissed reports of possible involvement as a pretext for “hostile action” against Tehran.
The men who boarded the MV Asphalt Princess were reportedly armed and are said to have ordered it to sail to Iran.
The United Kingdom Maritime Trade Operations (UKMTO) had initially warned ships of an incident before declaring a “potential hijack” hours later.
On Wednesday, the UKMTO tweeted that those who boarded the vessel had left, adding: “Vessel is safe. Incident complete.”
The incident occurred less than a week after an oil tanker operated by an Israeli-owned company was attacked by a drone off Oman, killing two security guards – one British and the other Romanian.
The US, UK and Israel blamed Iran for the attack – a claim it strongly denies.
BBC Security Correspondent Frank Gardner says the MV Asphalt Princess is owned by a Dubai-based company that had one of its ships hijacked two years ago by the Iranian Revolutionary Guards.
He says that, according to reports, up to nine armed men boarded the vessel as it neared the entrance to the Strait of Hormuz, through which about a fifth of the world’s maritime oil supplies passes.
Earlier in the day, four oil tankers reported that they were “not under command”, which usually means that a vessel has lost power and cannot steer. One of the ships later began moving, the Associated Press news agency reports.
Iran’s foreign ministry said reports involving several ships on Tuesday were “suspicious” and warned against any effort to “create a false atmosphere” against Tehran.