The monster crabs, which can weigh up to 25lb and have a claw-span of more than three feet, are proving so resilient that scientists fear they could end up as far south as Gibraltar.

Energised by a mysterious population explosion a decade ago, whole armies of the crustaceans - known as the Kamchatka or Red King Crabs - have already advanced about 400 miles along the roof of Europe, overwhelming the ports of northern Norway.

They now number more than 10 million and have reached the Lofoten Islands off north-west Scandinavia, leaving in their wake what one expert described as "an underwater desert".