Hundreds of birds have been washed-up along the south coast, covered in an unidentified "creamy, waxy substance".

The Royal Society for the Protection of Birds (RSPB) said the guillemots, a kind of auk, were discovered on Lyme Bay near Weymouth, the coast of of Portland in Dorset, and in Cornwall.

Many of them have been taken to West Hatch Animal Centre in Taunton, but attempts to clean them have been hampered by not knowing what the substance is, said RSPB official Grahame Madge.

"At the moment, the best guess is there are around 100 birds ashore, and there are concerns the birds are affected in as widespread a region as from Cornwall to Sussex," he explained.

"So we could be dealing with quite a large incident as all these birds could be proved to come from the same pollution incident.

"We are urging the Government to identify the source of the pollution and the pollutant."

Peter Venn, the manager of the RSPCA in West Hatch, Somerset, said: "The numbers of birds arriving in to our centre are growing and we are doing all we can to help them - but it is too early to tell how successful these attempts will be.

"We do not know what this substance is or where it has come from yet, but we do know it is not fuel.

"It may be byproduct from manufacture, but at this stage we just do not know.

"We would urge anyone who finds any of these birds to contact the RSPCA on 0300 1234 999.

"There are also reports of the sticky substance washing up on the beach, so we would urge people walking their dogs in the area to also be careful."

A spokeswoman for the Maritime and Coastguard Agency said: "We have received reports of seabirds being washed ashore covered in a white, waxy substance, from Cornwall to Portland, Dorset."

Dorset County Council warned members of the public about handling distressed birds on the south coast.

"While the substance is being identified, agencies are urging people to avoid coming into contact with the birds and to keep pets away from the shoreline," a spokesman said.