Coastwatch Ireland has threatened legal action against Meath County Council over asbestos it says it has found on land beside the Boyne estuary, which is within the council boundary.
Coastwatch spokeswoman, Ms Karen Dubsky, said that consultants the organisation hired had confirmed that blue and white asbestos had been found on the south side of the river.
The land is owned by Drogheda Port Company. Its chief executive, Mr Paul Fleming, said: "We believe Meath County Council are the relevant authority and we believe we have met all their requirements in relation to this matter."
It is understood the company bought the land in recent years while the asbestos is understood to be up to 30 or 40 years old.
Coastwatch's consultants said parts of the land were slumping, and they found pieces of asbestos on the surface of land banks.
The group was considering legal action unless remedial works were undertaken, Ms Dubsky said.
"Under the Waste Management Act we are allowed to take action and we have sent a letter to Meath County Council asking them to examine the site and characterise it, make it safe and close the boundaries. Otherwise we will go to court."
A county council spokesman said: "As far as we are concerned, the advice we gave on how the matter should be handled was complied with by Drogheda Port Company. We note that the Department of Environment and Local Government are investigating a complaint in relation to the matter and we will provide them with whatever information we have about the site."