In a scene more reminiscent of James Bond – or Doctor Evil in the Austen Powers movies – officers discovered the reptile in the bottom of an apartment building in St Petersburg, Russia.
They had arrested a 40-year-old man on suspicion of illegal possession of weapons and were searching his home in Peterhof for guns and explosives in November, police have revealed.
After finding ammunition in the house, officers entered the dark basement where the two-metre-long beast emerged from a muddy pool.
Happily for the officers, it quickly submerged back into the grey water.
Local media said the reptile is a Nile crocodile, which should be living in much warmer climes than the Russian city where November temperatures average 1C.
Residents of the block said the crocodile’s owner has at least four other reptiles.
A statement from the Ministry of Internal Affairs said: “In the basement of the house, operatives found a crocodile.
“During the search, no incidents related to the reptile occurred.
“The police reported this fact to the veterinary service to decide the crocodile’s fate.”
It is not known what authorities chose to do with the animal.
The Nile crocodile is Africa’s largest freshwater predator and is considered the second largest living reptile in the world, after the saltwater crocodile.
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They are known to be very aggressive and are not fussy about their prey, killing hundreds of humans every year.
The beasts, who can live to 100 years old and weigh up to 550kg, are social animals who bask and hunt in groups.