A new slick has been formed from oil leaked from the stricken MSC Napoli as concerns grow for local wildlife.
Many birds need to be cleaned of the oil stuck to their feathers
The Maritime and Coastguard Agency said the slick was several kilometres long and 30 metres wide and was formed from oil leaked from the ship on Tuesday.
Attempts were being made to contain the oil with booms and no more was leaking, a spokesman added.
Work is continuing to pump 3,500 tonnes of fuel oil from the ship, while some 600 birds are estimated to have died.
The MCA added on Wednesday afternoon that the new slick was moving southwards away from the stranded ship and at the moment was moving out to sea.
Meanwhile, an RSPCA centre, where 420 birds had been taken by Wednesday, estimated that only 40-50 could be cleaned and freed.
The Royal Society for the Protection of Birds reported that they had had reports of 1,000 birds affected by oil, mostly guillemots, and estimated 600 would have died.
Maritime experts believe structural damage to the Napoli caused it to start 'hogging'
The weakened hull causes a ship's bow and stern to sag
The effect is made worse by rough seas
The Napoli suffered structural damage during storms last Thursday and was deliberately grounded a mile off Branscombe to stop it breaking up in deep water.
Since the grounding 200 tonnes of oil have leaked into the sea.
The procedure to remove the oil from the ship is proceeding slowly, with around 30 tonnes an hour being pumped out.
MCA spokesman Mark Clark said: "It is going to be a sticky horrible job."
By midday on Wednesday more than 275 tonnes had been moved from 'portside tank six' and oil was to start being pumped from 'portside tank five', the agency said in a statement.
"Salvors are working in extremely difficult conditions, for example having to climb through small manholes in the deck, wearing breathing apparatus to insert hoses and move them about within the structure of the tank in order to suck out the oil," it added.
The MCA said it could be a year before the vessel and its contents were removed.
Identified fuel tank contents given by MCA on 23 January
Scavengers are no longer being allowed on the beach, with police asking people carrying objects from the ship's cargo to declare it before they leave and fill in the relevant forms, or surrender the property.
Those failing to do so could be arrested for theft, police said.
Branscombe Parish Council chairman John Bass said the influx of scavengers had scared locals and he would be seeking assurances from police that it would not happen again.
"I likened it to a plague of locusts coming to a small area and sweeping everything away."
A platform is being constructed next to the beach so contractors can cut up and remove containers and other cargo.