Two shipwrecks found during a failed search for Malaysia Airlines flight 370 were merchant vessels that sank in the 19th Century, researchers say.

The ships, discovered 2,300km (1,400 miles) off Western Australia, have been narrowed down by experts to a handful of coal-carrying British vessels.

Both merchant ships vanished without a trace more than 140 years ago.

The location of MH370 remains unknown more than four years after it disappeared, carrying 239 people, en route from Kuala Lumpur to Beijing.

Satellite images of possible debris suggested the plane had gone down in the Indian Ocean, south-west of Australia.

However, no sign of the plane was found during the search, which was suspended in January last year.