Three containers holding disinfectant have been washed up on the shore at three separate locations in Lincolnshire.
Lincolnshire Police cordoned off an area surrounding Trunch Lane in Chapel St Leonards on Thursday morning after a large barrel of disinfectant was found washed up on the shore.
East Lindsey District Council has now confirmed that two other containers, again believed to be disinfectant, were found at Moggs Eye and Anderby Creek.
The tubs contain Tribac, a disinfectant that could be hazardous to the environment, as well as being corrosive and potentially dangerous to the human respiratory system.
The substance is highly toxic to aquatic life and can leave long lasting effects, as well as being dangerous for other forms of wildlife.
On Chapel Beach, around 12 birds died as a result of the disinfectant spill across a 1km stretch of the area.
It is unknown how the containers made it to the shore or where they came from, but work is underway to remove them safely.
The dead birds have been removed by the department for environment, food and rural affairs (Defra) and will be investigated.
The Lincolnite has contacted East Lindsey District Council for an update, but are yet to receive a reply at the time of publication.