Phocine Distemper Virus (PDV) has killed about 1,000 animals, said Mike Hogg, Chief Inspector with the Royal Society for the Prevention of Cruelty to Animals (RSPCA) on Wednesday.

Infected seals found alive are being kept in long-term quarantine at the RSPCA's animal hospital at East Winch near King's Lynn in Norfolk.

So far more than 100 have been taken there and about 40 have been saved.

Forty seals have been saved

"We are looking at next spring before they will be able to be released back into the wild," Mr Hogg said.

RSPCA inspector Mark Thompson spent Wednesday looking for live seals on North Norfolk beaches.

All he found was dead ones brought in by the tide.

"At the moment we are getting a lot more dead adults come up on the beach.

"Whether they are dying out at sea and being washed in we are not sure but they don't seem to be coming up onto the beach alive to be taken to the hospital at East Winch."

The last 1998 outbreak of the virus claimed an estimated 1,500 seals off the north Norfolk coast.

There is no known treatment for the virus, and no way of preventing it.