Negotiations with pirates who seized a vessel containing $100m worth of oil are taking place
Vela International Marine Ltd also confirmed it had gained assurances that none of the 25 hostages, including two Britons, on board the Sirius Star will be harmed.
The vessel, which has been reportedly reached the coast of north Somalia, was captured some 450 nautical miles east of Kenya.
The US Navy described the taking of the 318,000 deadweight tonnes ship as an "unprecedented attack".
The supertanker, owned by a Dubai based company, is carrying more than $100m dollars' worth of oil and is the biggest vessel yet seized.
The ship is now thought to be heading for the Somali port of Eyl, whereupon it is believed the crew, which includes two Britons, will be taken ashore and ransomed.
The US Navy has told Sky News they have been warning shipping companies to do more to protect their vessels and their crews but to no avail.
Commander Jane Campbell said: "This is unprecedented in recent attacks.
"But we expect now that ... the ship will be directed to proceed to an anchorage location off the coast of Somalia."
Admiral Mike Mullen, chairman of the joint chiefs of staff, suggested the ship's captors are not to be underestimated.
"They are very good at what they do," he said. "They are very well armed, tactically they are very good and so once they get to a point where they can board it becomes very difficult to get them off, because clearly now they hold hostages."
Sirius Star, which is owned by Saudi Aramco, is carrying 25 crew members from Croatia, Britain, Philippines, Poland and Saudi Arabia, according to a US Navy statement.
The International Maritime Bureau has reported that 63 ships have been attacked off Somalia in the three months leading up to the end of September, of which 26 were hijacked with 537 crew members taken hostage.
Of those, 12 vessels and 243 people were still in the hands of pirates.