Hundreds of birds affected by an oil slick at sea have washed up on the coast of East Anglia over the past 10 days.

More than 600 oiled birds have been collected on the Suffolk and Norfolk coasts.

That is more than double the number being treated in Spain following the sinking of a tanker, according to the RSPCA animal charity.

The organisation said on Thursday birds had been washed up between Lowestoft, Suffolk, and Great Yarmouth, Norfolk.

RSPCA workers are trying to rescue birds

A spokeswoman for the RSPCA said: "We believe this is the worst incident of its kind off the east coast dealt with by the RSPCA .

"We believe there is an oil slick offshore.

"It may be oil leaking from the fuel tanks of an old wreck, but no one has yet identified the source."

The spokeswoman said it was not known what type of oil it was.

Birds washed

Guillemots, razorbills, great crested grebes and red-throated divers have mainly been affected by the slick.

After collection from the beach, the birds are initially being taken to the RSPCA wildlife hospital in East Winch, Norfolk, for washing and care.

When the hospital is full, they are taken to the charity's wildlife hospitals in Somerset and Cheshire.

Seals treated

Some of the grebes who were the first affected by the slick have been nursed, cleaned and re-released, said the spokeswoman.

The slick is the second major incident to be dealt with by the East Winch centre this year.

In the summer it treated seals affected by the phocine distemper virus, which wiped out large numbers of seals in the Wash area of Norfolk.

Anyone who finds an oiled seabird can call the Royal Society for the Prevention of Cruelty to Animals (RSPCA) on 0870 5555 999.