Amsterdam  - Swans are famous in the animal kingdom for their monogamy and lifelong loyalty to their spouses - as drivers in the Netherlands found out on Tuesday.

After one swan was struck and injured by a car on the country's busiest motorway at rushour, its partner refused to leave the scene - forcing police to temporarily close the stretch of highway.

Tailbacks were seven kilometres long at the worst point of the holdup, before both swans were eventually taken away by vets - themselves delayed by an hour due to the congestion.

The first swan is said to have severe injuries. (dpa)