Scientists say a waxy, sticky substance that has left hundreds of stricken seabirds washed up on the coast is a "refined mineral-based oil mixture" and not palm oil as first suspected.
Hundreds of the birds, mainly guillemots, have been treated by the RSPCA after they washed up on the shore covered in the glue-like substance while many other birds have died.
Environment Agency staff have told reporters that, after analysing water samples, they now believe the pollutant is a refined mineral oil. It was earlier thought the mystery substance may have been palm oil or similar type of substance.
A spokesman for the Environment Agency told the Press Association: "The results show that it is a refined mineral-based oil mixture, but not from an animal or vegetable-based oil, which rules out palm oil."
RSPCA deputy chief inspector John Pollock, who has been leading the rescue mission in Dorset, earlier described the substance as "white, odourless and globular".
A rescue operation was launched after more than 100 seabirds were washed up along the Westcountry coast and this number has been rising all the time with more than 200 birds now affected. It is not known how many of the birds have died.
The guillemots were found washed along the coastline stretching from Chesil Cove and Portland in Dorset to Torquay in Devon and down to Cornwall. Rescue teams have been finding the birds washed up along the shoreline every day since Thursday.