The 23 birds covered in cooking oil were at risk of drowning or dying of hypothermia
Volunteers at a bird sanctuary have started the painstaking process of cleaning 23 swans covered in cooking oil at a lake in Swansea.
The birds were rescued by the RSPCA and taken to the Tinker's Hill Rescue Centre in Amroth, Pembrokeshire.
The lake in Swansea's Enterprise Park was contaminated by vegetable oil and the spill is being investigated.
Volunteer Maria Evans said unless they were fully cleaned the swans faced death by drowning or hypothermia.
She was already looking after 15 swans prior to the spill 12 days ago.
"It was very short notice," she said.
"We've put temporary accommodation in our big bird of prey barn so they are having to share with somewhat noisy birds of prey."
The centre helped deal with the fall-out of the Sea Empress disaster on the Pembrokeshire coast in 1996, but Ms Evans said this was the largest number of birds they had dealt with in one go.
"When the RSPCA inspector opened the doors of his van the smell nearly knocked you off your feet.
"It just smelt like really nasty old chip oil.
"All of them have got it on their necks, some of them have got it on their undercarriage and a lot of them have it all over them.
"The worst danger for them if they are not waterproof and they get waterlogged they could just drown, or because they have not got any insulation between the feathers they could die of hypothermia."
The RSPCA officers rescued the birds from the lake at Fendrod business park near Llansamlet.
Ms Evans said cleaning each swan was a two-person job but she had volunteers who helped out.
Geese on Fendrod lake, pictured in 2007
Once the oil is washed off, the swans need to be dried using heat lamps.
This is done in a temporary cabin loaned to the sanctuary by the engineering contractor Costain, which is working on a nearby by-pass.
"I'm hoping that they will only be here for around two weeks. They can usually be washed, treated and rehabilitated in 14 days," added Ms Evans.
The Environment Agency said there had been no new spillage since the weekend before last.
It said officers had traced the source and collected samples and it would consider taking action against those responsible.
A spokesman said: "Officers have investigated and discovered there is no further pollution incident.
"The likely explanation for more oil being discovered is wind dispersing the oil to other areas of the lake.
"Residual oil from the incident could also be washed through pipe by rain but this should be contained by absorbent booms placed by contractors."