A CHEMICAL cloud that forced coastline evacuations across East Sussex on Sunday is “very unlikely” to have floated over from northern France, authorities have said.

Some 150 people required treatment for stinging eyes, sore throats and vomiting, but the effects of the unknown substance were “mostly minor”, according to Sussex police.

Despite the incident, thousands are expected to flock to beaches along the coastline on Bank Holiday Monday as temperatures reach up to 25°C (75°F).

In the past, chemicals have drifted across from European industrial units, but weather models indicate this was not the case on Sunday, according to the Met Office.

Forecaster Jay Merrell suggested a vessel in the English Channel may have been responsible for the noxious haze, but stressed nothing conclusive had been proven and that inquiries continue.

Sussex police said: “Neither the gas nor its source have been established, but agencies are continuing to investigate and have not ruled out either on-shore or off-shore locations, although it does appear that it did sweep in from the sea driven by on-shore breezes.

“However, weather models suggest that an onshore source in northern France is very unlikely.”

Bob Jefferey, of the Royal National Lifeboat Institution Eastbourne division, said: “Whatever it was, it smelled like burnt plastic. It hung about and didn’t move yesterday because there was no wind. The cloud seems to have dispersed today though.”