Around 4,800 Mazda vehicles headed for Canada and the US are on the Mitsui OSK Lines' ship Cougar Ace which has run into trouble off the Alaskan coast.

"Although it is reportedly still afloat, the vessel is on its side," Mazda said on Thursday (27 July).

The automaker said it did not know what caused the incident or the extent of the damage to the vehicles it is carrying.

Around 60% of the cars are the 3 model and about 30% the new CX-7 crossover as yet sold only in North America. The vehicles were headed to the ports of Vancouver in Canada and Tacoma, Washington state and Hueneme in the USA.

The automaker added that a plan for salvaging the vessel is being developed and will be undertaken by Mitsui OSK Lines as soon as possible.

It declined to provide any more information saying only: "Mazda will wait until the situation has been fully evaluated and understood."

Media reports this week said the ship got into trouble on Sunday evening when it began taking on water and listing to one side. Rescuers from the Coast Guard and Alaska Air National Guard late on Monday saved 23 crew members from the ship after they sent out an SOS.

All 23 crew members were hoisted into three helicopters and taken to Adak Island in the Aleutians, 230 miles to the north of the stricken ship, according to the Associated Press (AP).

The Singapore-flagged Cougar Ace's owner told AP that the vessel was carrying 4,813 cars and that there were no reports of any going overboard - a spokesman said typically vehicles are securely fastened.

The crew had not known what had caused the ship to list nor where any water was coming in.

In a statement on Thursday, Mitsui OK Lines (MOL) said the vessel was floating in a stable condition though it remained listed to one side.

The company finally managed to speak with the captain on Wednesday and he confirmed that the vessel started listing during work to adjust ballast water.

MOL said a possible cause of the listing was instability developed during the ballast water adjustment process, rather than external forces such as a collision with unknown object or grounding.