A reptile enthusiast investigating a call from a man he thought "had been drinking", found a metre-long Nile crocodile lazing in the pool of a Pretoria suburb, the Pretoria News daily reported on Wednesday.

"I received a phone call on Sunday night with this man claiming he had a crocodile in his swimming pool," said reptile expert Pieter Brouwer.

"My first thought was that the man had been drinking but after getting there, even I was surprised to see it (the crocodile)," he told the paper.

Submerged at the bottom of the pool was the croc which, although not considered extremely large, could still deliver a nasty bite.

Brouwer dived into the swimming pool and captured the creature.

"The chlorine in swimming pools is not good for crocodiles — it burns their eyes," Brouwer told the paper, adding he planned to take it to a privately owned zoo.

How the reptile, with razor-sharp teeth, made its way into a residential swimming pool still remains a mystery but upon closer inspection, it was noted that the crocodile had two scales cut off from its tail, the paper said.

"The crocodile could have escaped from a nearby breeding farm," said Brouwer, as they are not indigenous to the Pretoria area.

He added that that owning or selling indigenous reptiles without the necessary permit was illegal.