Boarders have left a tanker that maritime sources had said was seized off the coast of the United Arab Emirates (UAE) and the vessel is now safe, Britain's maritime trade agency reported on Wednesday.

The United Kingdom Maritime Trade Operations (UKMTO) said the incident is "complete" but gave no further details in a warning notice based on a third-party source.

Three maritime security forces told Reuters on Tuesday that the Asphalt Princess tanker had been seized by suspected Iranian-backed forces, which Iran denied.

Iran's senior armed forces spokesman, Abolfazl Shekarchi, had on Tuesday denounced reports of maritime incidents and hijacking in the Gulf area as "a kind of psychological warfare and setting the stage for new bouts of adventurism."

The U.S. State Department had said it was looking into reports of a maritime incident in the Gulf of Oman, but that it was too early to offer a judgment.

Tensions have simmered in the region after an attack last week on an Israeli-managed tanker off the Omani coast killed two crew members and was blamed on Iran by the U.S., Israel and Britain. Iran has denied responsibility.

The UKMTO initially reported a "non-piracy" incident on an unnamed ship before upgrading its description.

Maritime security analysts at Dryad Global and Aurora Intelligence identified the endangered ship as the Panama-flagged Asphalt Princess.

The MarineTraffic website, which categorizes it as an asphalt and bitumen tanker, said it was traveling to Sohar, a port on Oman's northern coast.