Norwegian oil tanker Front Altair was still afloat after a reported attack in the Gulf of Oman on Thursday, the chief executive of the company that owns the vessel told AFP, denying reports it had sunk.
"I can confirm that the vessel has NOT sunk," Frontline Management chief executive Robert Hvide Macleod wrote in a text message to AFP.
The 23 people who were on board were "all safe", he added.
The Front Altair and another tanker were reportedly attacked in Thursday's incident, which sent world oil prices soaring.
Iran's official news agency Irna had earlier cited foreign media reports that one of the two vessels had sunk.
The Norwegian Maritime Authority said the 111,000-tonne Front Altair, a Marshall Islands-flagged vessel, was "attacked" and that there were three explosions, but no injuries reported on board.
Frontline provided no other details. According to the Norwegian Maritime Authority, the ship's crew had boarded a passing vessel.
Norwegian authorities called on their ships to exercise extra caution in the region, and "to stay well clear of Iranian waters until further notice".
The Norwegian foreign ministry said it was "concerned" over the situation in the Gulf of Oman.
"This type of incident contributes to a further escalation of tensions in the region," ministry spokeswoman Astrid Sehl told AFP in an email.