HUNDREDS of dead seagulls have been washed up on the North-East coast in the past few days.

Most small stretches of beach in Hartlepool were said to be covered with dead birds at the weekend.

The incident, the second of its kind in two months, has baffled experts, who cannot find a cause of death.

In November, the Environment Agency, the RSPCA and the coastguard were swamped with calls about dead birds on the shore, and fishermen reported seeing hundreds of dead gulls floating out at sea.

Post-mortem examinations failed to reveal the cause. The Environment Agency carried out seawater tests, but they were inconclusive.

Animal collection officers from the RSPCA were collecting the birds on Sunday and yesterday.

A spokeswoman said: "Once again we have alerted the Environment Agency and they will be carrying out tests.

"There have been about 70 birds washed up since Friday, but we think there could be hundreds on the North-East coast.

"The birds are healthy-looking, and not emaciated. They are not covered in any kind of oil, so it is a mystery. From an animal welfare point of view it is very concerning."

Anyone with information about injured or dead gulls should contact the RSPCA on 0870-5-555999.