The Japanese owner of the giant cargo ship that has been blocking Egypt's Suez Canal since Tuesday has apologised for the disruption to global trade.
Shoei Kisen Kaisha said it was trying to resolve the situation as soon as possible, but that dislodging the Ever Given was proving extremely difficult.
The 400m-long (1,300ft), 200,000-tonne vessel became wedged across the canal amid high winds and a dust storm.
At least 150 ships are now waiting to pass through the vital maritime route.
About 12% of global trade passes through the Suez Canal, which connects the Mediterranean Sea to the Red Sea and provides the shortest sea link between Asia and Europe.
An alternative route, around the Cape of Good Hope on the southern tip of Africa, can take two weeks longer.
The vessel, which is operated by Taiwanese transport company Evergreen Marine but called the Ever Given, is currently wedged diagonally across the waterway.
"In co-operation with local authorities and Bernhard Schulte Shipmanagement, a vessel management company, we are trying to refloat [the Ever Given], but we are facing extreme difficulty," the owner, Shoei Kisen Kaisha, said in a statement on Thursday.
"We sincerely apologise for causing a great deal of worry to ships in the Suez Canal and those planning to go through the canal," it added.
Industry sources told Reuters news agency that even if the Ever Given was refloated quickly its owner and insurers faced claims totalling millions of dollars for the delays and extra costs accrued by other companies.
Toshiaki Fujiwara, an official at Shoei Kisen Kaisha, told AFP news agency that the ship had an insurance policy, but that he was unaware of the details or any costs involved at this stage.
"It's just the beginning," he said.
Global crude oil prices were up more than 6% on Wednesday after traffic through the canal was suspended, though they fell slightly on Thursday
A flotilla of eight tug boats resumed efforts to move the Ever Given at high tide on Thursday morning after stopping overnight, Egyptian officials said.
Dredgers and diggers have also been clearing sand and mud away from the bow of the vessel, which is sitting on the side of the canal.
The head of a Netherlands-based salvage company assisting the operation warned that it could take weeks to dislodge the boat and that containers might have to be lifted off to lighten its load.
"We can't exclude it might take weeks, depending on the situation," Peter Berdowski, the CEO of Boskalis, told the Dutch TV station NPO.
"It is like an enormous beached whale. It's an enormous weight on the sand," he added. "We might have to work with a combination of reducing the weight by removing containers, oil and water from the ship, tug boats and dredging of sand."/ newtimes
