A city worker was shocked when he spotted what he believed to be a crocodile sunbathing on a rock in the River Thames in London.

The office worker called Ben posted a picture online after spotting the ‘reptile’ while out on his lunchbreak with a colleague on Millwall Outer Dock on the Isle of Dogs.

He told News Shopper: “To our horror we spotted what appears to be some sort of large reptile. My colleague thought it might be a dinosaur but I corrected him that it looked more like a crocodile.”

Thankfully a nearby sailing and watersports centre cleared things up by confirming the ‘crocodile’, which they dubbed ‘the Dockness Monster’, was actually a pile of old rope.

[Related story: Mysterious skeleton found on banks of Thames

In a post on Facebook, Docklands Sailing and Watersports Centre said: “We can confirm that it is not an alligator but a big bundle of… ROPE!”

The centre’s manager Judi Sanders said: “This is quite funny although I am sure some people would be taken in by this and not want to come here.

She added: “It is rope, the water gets tested independently every other week.”

The centre also confirmed regular visitor Sammy the seal remains safe and sound.

Picture credit: The Docklands Sailing and Watersports Centre