He had finished swimming when his eyes started stinging. He looked around and saw everyone on the beach also rubbing their eyes and coughing in what he described as "all sorts of strange behaviour".

He told BBC News: "Then looking out towards the water, there was just this crazy foggy haze rolling in off the sea out of nowhere. It was definitely out of the ordinary considering it was a nice clear sunny day 10 minutes beforehand.

"It was stupidly busy and it was a boiling hot day. It emptied in about 10 minutes which was quite staggering considering the amount of people who were there."

The beachfront is popular with dog walkers and is a busy spot for tourists and locals enjoying the bank holiday sunshine.

Dan Sankey wrote on Twitter: "Beautiful afternoon at Birling Gap cut short by some weird mist, burning everyone's eyes which led to the beach and cliff being evacuated."

Sameer Jadhav tweeted: "Birling Gap some weird gas leak. People crying. Ambulances called. Don't go to Birling Gap at the moment".

The effects felt by those caught in the cloud “prompted emergency services to warn people to stay away from the beaches and to keep doors and windows closed if living near the coast”.