A British expat has discovered hundreds of stranded “evil-eyed” pufferfish – each armed with a poison more deadly than cyanide.

Tess Gridley, from Sheffield, encountered the mass stranding at Muizenberg Beach in Cape Town, South Africa, while walking with her family.

Now the South African government has identified the creature as the lethal evileye pufferfish and warned locals to steer clear.

Dr Gridley, a scientist who moved to Africa in 2009, estimated that hundreds had washed up.

“The beach is 200 metres from our house and we were on a family walk,” she said.

“I can’t say how many were there as I only looked in a small area – I was with my kids and dog, and prepping for fieldwork so it was a short visit.

“But if you did count it would have exceeded hundreds.”

In a statement, South Africa’s Department of Environment, Forestry and Fisheries said the species carried a killer neurotoxin called tetrodotoxin.

It’s a poison more lethal than cyanide and it causes death by respiratory failure after paralysing the diaphragm.