Oil-soaked birds have been discovered dead on Chesil beach near Portland.

The corpses have been found along the iconic 20 mile-long shingle bank and the oil is thought to have been flushed out of a passing ship.

The birds that have been affected are mostly gannets and they live at sea at this time of year.

After getting oil in their feathers they don’t have the energy to make it to the shore and slowly die, their bodies being washed up later.

Conservationist Steve Trewhella made the discovery as he walked along the iconic coastal feature on the Jurassic Coast.

He spotted about a dozen casualties, all beyond help, in just a small area of the shore.

He said: “The birds were covered in a treacley oil at Chesil Beach and at Chesil Cove. They were caked in it and were the most oiled birds I’ve ever seen.

“I found ten birds in just a small area and Chesil beach stretches for 20 miles, so who knows how many dead birds there might be.

“The gannets are sea-going birds and they live out at sea at the moment and if they dive into the oil or get stuck in it then they haven’t a chance.

“I think this was engine oil that was flushed out of a passing ship, rather than crude oil.

“But the oil is here now and it will be here for the rest of the year. While I was at the beach some surfers came down, took one look and refused to go into the water.

“I am always amazed when a heath fire can generate so much media cover.

“Yet our oceans cover 70 per cent of the world’s surface; we overfish them, pollute them, use them as landfill and all look on, thinking it will just repair itself, it is very big after all.

“I am an active supporter of SAS – Surfers Against Sewage – and these types of incidents show just how much work there is to do to keep our coasts healthy.”

The Environment Agency has not received any official reports of a spill and the Coastguard had not been informed either.