A thief walked unnoticed out of a Norwegian aquarium carrying a crocodile at the weekend and now risks losing a finger or two, the head of the aquarium said on Monday.

"I think whoever did this knew what they were doing," Bergen aquarium director Kees Oscar Ekeli told Reuters, suggesting the young crocodile was smuggled out in a bag during the busiest hours on Saturday.

The stolen reptile, named "Taggen" (Spike), is a 70 centimeters (2.3 feet) long smooth-fronted caiman also known as Schneider's dwarf caiman (Paleosuchus Trigonatus).

Taggen eats "a good mix of fish and meat" and can grow to be about 2.5 meters (8.2 feet) long. "It has a solid bite. Considering it is not bigger than it is, you could lose a few fingers, but no vital organs," Ekeli said.

It is normally found in much warmer habitats in South America and is one of the world's smallest species of crocodile.