A local conservation charity has expressed its concerns over “gunk” spilling out of Pembroke Power station into the surrounding sea and foreshore.

The effluent was spotted by Sea Trust volunteers and supporters while heading out on a wildlife survey to the Celtic Deep.

Conservationists also noticed an acrid smell in the area but could not definitely confirm it was coming from the foamy looking substance.

Sea Trust founder, Cliff Benson said he had contacted the Natural Resources Wales hotline and had been told that the effluent was a biological emission that was harmless. However he questioned just how innocuous it was.

“I was told it was organic with no environmental impact," he said. "However I wouldn’t want to bathe in it and I wouldn’t want my kids playing in it. It didn’t look good or smell good.

“It’s not a good advertisement for the power station,” he added. “We are told it’s going to be a nice clean lovely thing. You pass by and see all this gunk coming out of it. They don’t seem to have done much of a job of cleaning it up”

He urged the owners of the power station to “come clean” about what the gunk is and to do a better job of cleansing the shoreline.”I wonder if anybody in the power station knew it was happening,” he added.

Huwel Manley, from Natural Resources Wales said: “We have been working with RWE Generation UK plc (RWE) to reduce the amount of foam which is generated through the power station’s operation, and they have recently installed new technology to tackle this.

“The foam is generated as sea water falls over the weir and combines with organic plant material.  It is likely to be particularly prevalent at the moment due to the high tides.

“While it is not dangerous in any way to the environment, we understand that it can cause alarm and RWE have committed to address the issue.”

A spokesman for RWE Generation UK added: "The foam currently coming from the Pembroke Power Station cooling water outfall is the same as the sea and beach foam which occurs naturally from time to time.

"It is harmless and is not caused by any form of pollution.

"RWE have commissioned a unique and bespoke project in order to reduce the formation and release of foam from the station.

"This work is underway with mechanical installation complete and commissioning due to be completed by the end of 2015."