Hundreds of seabirds have been caught in an oil slick eight miles off the coast of East Anglia.

Dead and sick birds have been washed up in Essex, Suffolk and Norfolk, and there are widespread reports of oil on beaches.

The Royal Society for the Protection of Birds (RSPB) says the five-mile slick was the result of a tanker washing out its tanks at sea.

However, the Maritime and Coastguard Agency says it does not yet know what caused the slick, which has already broken up.

Some captains treat the sea like an enormous dustbin

RSPB spokesman

Sharon Thompson of the RSPB said the incident showed oil pollution was not limited to major accidents such as the sinking of the Prestige off the coast of Spain.

"Around the UK coastline, far more oiled birds are reported every year with incidents like this, which undoubtedly are caused by unscrupulous tanker captains washing out their vessels' tanks at sea," she said.

Debra Tough told BBC Radio Norfolk the beach in Great Yarmouth had been badly affected.

She said she had spotted a dead seagull and a struggling guillemot covered in oil.

"When we came off the beach we noticed that our wellington boots and the dog's paws were absolutely caked in thick oil," she said.

RSPCA workers are trying to rescue birds

An RSPB spokesman said international legislation was needed to tackle the problem of irresponsible captains.

"Some captains treat the sea like an enormous dustbin," he said.

But a spokesman for the Maritime and Coastguard Agency said slicks could sometimes be caused by storms whipping up oil from the seabed.

Laboratory tests are being carried out to find out the cause.

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