Faeces have been found floating off Brighton beach this morning.
An Environment Agency spokesperson said it was aware of the report and was working with Brighton and Hove City Council.
They added it is not unsual in wet conditions for some watered-down effluent to be flushed out to sea to prevent flooding on the mainland.
A Surfers Against sewage spokesman said: "At 7.15 this morning the P2P Swimming Club entered the water for their morning swim, however only metres from the West Pier the swimmers found themselves in the middle of a slick of raw sewage.
"Gentle winds and calm waters mean it’s a great day to enjoy the water, if you are a Brighton water user this incident has the potential to seriously impact upon your health.
"Once again UK water users have been forced to risk their health to take part in the sports they love.
Paul Smith MD of Swim UK, counted 20-25 pieces of solid excrement in his immediate vicinity, and said “It’s the worst we’ve seen it in over 30 years, the slick stretched as far as the eye could see”.
P2P Swimming Club in Brighton immediately left the water and have suspended all swims for the next couple of days and are taking precautions with their health.
A Southern Water spokesman said: “We have investigated these reports and can confirm that there have been no releases from any of our facilities which could affect this bathing water.”
- Did you see the sewage? Call the newdesk on 01273 544525