Two crocodiles have been reported missing from a mobile zoo in Sydney's south-west. 

Police were called to Sandy Point about 5.30pm on Friday after staff discovered a pair of crocs, aptly named Snap and Crackle, were not in their enclosure.

The two reptiles, each measuring in at around one metre in length, are presumed stolen, with no signs of forced entry. Police say the crocodiles were taken from their enclosure.

Investigators are calling for public assistance as concerns are held for the wellbeing of the animals, which must remain in a controlled environment.

It is understood the crocodiles are unlikely to survive if they spend too long in temperatures below a certain threshold.

Police are urging anyone with information as to the whereabouts of the crocodiles to contact Crime Stoppers on 1800 333 000 or use the Crime Stoppers online reporting page.