Wexford County Council is investigating reports of "traces of oil" washing up on beaches and possible oil deposits on some wildlife on the Wicklow and Wexford coastlines.
Oiled seabirds are being reported along the coasts of the two counties, BirdWatch Ireland has said.
The source of any oil spill has not yet been established but inquiries are under way. The council's environment staff, the National Parks and Wildlife Service and the Irish Coast Guard are actively monitoring the situation, it said.
Anyone with more information on the oil spill has been asked to contact the Coast Guard with any details, while anyone who has seen evidence of oil deposits on local beaches or on wildlife has been asked to contact the council.
"Unfortunately, we expect more oiled birds will be found in the coming days," BirdWatch Ireland said.
It has been reported locally that at least three oiled birds have been found along the coast and BirdWatch Ireland has said the birds affected include guillemots and that the situation is being monitored.
It said it had received several phone calls about the matter, mainly from the north Wicklow area including people on the coast around Greystones and Newcastle.
"This situation highlights yet another threat posed to our already vulnerable seabird populations," it said.
BirdWatch Ireland has called for a formal national oiled wildlife response plan.
It is understood one of the Irish Coast Guard search and rescue helicopters, based in Waterford, was tasked with flying along the east coast this morning in an attempt to find the source of any spill.
The National Parks and Wildlife Service said it is aware of reports of birds being washed up on parts of the Wicklow and Wexford coast and is "monitoring the situation" and liaising with local authorities and other relevant agencies.
Reports of oiled seabirds came in from number of locations, says rescue service
Kildare Wildlife Rescue said reports of oiled seabirds, predominantly Common Guillemots, began coming in from a number of locations yesterday afternoon, between Carnsore Point in Co Wexford and Dalkey Island in Dublin.
Along the areas "notably affected" were Greystones, Newcastle Beach, Brittas Bay, Wicklow town, Curracloe in Wexford, and others.
The rescue service said it is likely an oil spill originated near the breeding or feeding grounds of the birds in the Irish Sea.
They are collaborating with the Oiled Wildlife Response Network, Birdwatch Ireland, Seal Rescue Ireland, and the National Parks and Wildlife Service to co-ordinate a swift and effective response to all reports of oiled birds.
"Unfortunately, many of the affected birds are still too mobile to contain and are in inaccessible locations in water or on coastal islands," a spokesperson for Kildare Wildlife Rescue said.
They have urged anyone who finds an oiled bird not to touch it but to report it, and the location, to their local authority.
