Up to 100 swans are being rescued from a marina in Lincoln after being covered in oil.

RSPCA officers have been removing the birds from Brayford Pool throughout Tuesday so they can be cleaned up at a centre in Norfolk.

The oil is thought to have come from a boat which sank on Monday following a rise in water levels caused by heavy rain.

The clean up operation could take several days and an investigation has begun into how the oil was spilled.

Obviously this oil is going to do them nothing but harm Dean Astill-Dunseith, RSPCA inspector

RSPCA Inspector Dean Astill-Dunseith who has been catching affected birds warned they could be poisoned by the oil if they do not receive treatment.

He said: "This morning we have received a call that a number of the swans are oiled up in the Brayford.

Poisoned feathers

"We have come down and we have found about 50% of the birds down here are oiled up, some of them quite badly.

A boat sunk in Brayford marina on Monday

"Obviously this oil is going to do them nothing but harm.

"When they start pruning themselves they are going to poison themselves.

"Some of them are so badly oiled up it affects their waterproofing as well so it has got to come off."

He said the birds will be taken to a wildlife centre in Norfolk which specialises in treating birds affected by oil spills.

"As I understand it a boat sunk in the high water a bit further down, possibly that is the cause of it.

"Unfortunately all we can do is sort out the ramifications of it."