A SMELL akin to “festering, hot sewage” plaguing an area of Southampton has left residents sleepless and disgusted.

Those who live in and around St Denys have said they have seen items floating in the River Itchen, and are left sickened by an awful stench.

The smell has been described as like “festering, hot sewage” which has stopped people from opening their windows during the heatwave.

Residents believe the stench is coming from the Southern Water plant nearby, claiming that the smell gets worse late at night.

But the Environment Agency has confirmed the smell is down to the heat.

A spokesperson said: “Our specialist officers believe the most-likely cause of the odour in this heat and what can be seen in the water is naturally-occurring algae.

“Anyone with new concerns, or who suspects other pollution in our waterways, can contact our 24-hour incident hotline on 0800 807060.”

Southampton City Council has said it is are aware of a small number of complaints about the odour.

Residents have said the smell is also “really bad”- by Northam Bridge, Bitterne Manor and Chessel Bay.

Resident Mike White took photos from Cobden Bridge which show what residents believe to be “toilet paper” floating in the River Itchen.

Another resident claimed she has seen “human waste floating down the river”.

Chris Zardis said he usually uses the river at high tide but said he is “abstaining for a little”.

“The stench around Northam Bridge is absolutely outrageous right now and I don’t know how people in the flats around Quayside Road are coping,” he added.

Marcin Tryka lives on Kent Road and said that late at night is when the “horrible smell” gets at its worst.

She said: “Smell is so awful it wakes me up. Closing all the windows doesn’t help at all.

“It gets into the property through all the vents and you can smell it coming through the floor boards on ground floor.

“With this hot weather it’s impossible to sleep with windows closed."