A team of investigators has been sent to the Suffolk coast to establish the cause of a mystery black ooze pouring from a water pipe into the sea.

Ipswich Star: A mystery substance was spotted leaking into the sea at Felixstowe. Picture: CONTRIBUTEDA mystery substance was spotted leaking into the sea at Felixstowe. Picture: CONTRIBUTED (Image: Archant)

The oil-like substance cast a large black shadow on the water after it was discovered leaking from a rainwater pipe on Felixstowe seafront.

Water company investigators were quickly informed of the slowly spreading slick when it was first witnessed by visitors and residents of the coastal town this afternoon.

The origin of the unpleasant smelling liquid has yet to be confirmed – but Anglian Water said the pipe is designed to carry only surface water.

A company spokeswoman said there was no reason any other substance to be found in the drains, and that it appeared a third party had wrongly flushed something away.

Ipswich Star: AW says the beach has now been cleaned after an oil-like substance poured out of an outfall pipe on Felixstowe beach. Picture: CONTRIBUTEDAW says the beach has now been cleaned after an oil-like substance poured out of an outfall pipe on Felixstowe beach. Picture: CONTRIBUTED (Image: Archant)

One day-tripper – a resident of nearby Trimley – saw a dark circle of water emerging as they stood looking out to sea near the Fludyers Hotel, in Undercliff Road East.

He was able to identify the pipe as Anglian Water’s surface water outfall.

“It was about 50 yards to the left of where I was standing,” said the visitor, who also took photographs of the sludge as it was draining from the pipe.

“I looked out and thought ‘what’s that shadow on the water?’ – but there were no clouds in the sky that would have cast such a shadow.

Ipswich Star: A mystery substance was spotted leaking into the sea at Felixstowe. Picture: CONTRIBUTEDA mystery substance was spotted leaking into the sea at Felixstowe. Picture: CONTRIBUTED (Image: Archant)

“On first inspection, it looked like oil – it had that sort of really dark blackness, but not the same consistency or smell. It had a very odd smell – one I can’t compare to anything else.

“It was clearly running down the rocks and into the sea – flowing steadily.

“Around the time I left, it was about 20ft out to sea – and growing.”

An Anglian Water spokeswoman said: “Our teams on their way to investigate reports of a black, oily substance coming from a surface water pipe in Felixstowe.

“Surface water outfalls are designed to take rainwater only. They take it away from roads, gullies and residential areas when it rains.

“There is no reason for any substance like this to be found in these drains, so at this early stage it looks as though a third party has wrongly put something down the drain.”