People are being told not to fish around Torness nuclear power station after an oil leak from an electricity substation on the site.
East Lothian Council yesterday advised visitors to two beaches next to the power station to stay out of the water and keep their pets away.
Now they have asked people not to fish in and around the beaches as well.
The alert came after the ScottishPower substation which is based at Torness suffered an electrical fault on Sunday, sparking a fire protection system into action and leading to oil and cooling water spilling into the drains.
Reports of discoloured water saw the local authority advise people using Thonrtonloch and Skateraw baeaches to stay out of the sea as water quality investigations were launched.
The fishing ban is in place for "at least the next 24 hours" the council said while waiting for the results of the water tests.
It added that while it is believed the situations is improving clean up work has been taking place with teams using spill kits to block drains and contain and collect as much oil as possible.
The council said it is believed the overflow has stopped but an absorbent boom had been installed as an additional safeguard.
The substation is operated by SP Energy Networks and located within the grounds of EDF’s Torness Power Station.
Tom Reid, the council's head of infrastructure, said: “Teams responded swiftly to this incident and, working together with partner agencies, we are closely monitoring and managing the situation to protect the local environment.
“We do believe it is an improving picture but, given the nature of the incident and the proximity of the beaches at Skateraw and Thorntonloch, we continue to ask members of the public to refrain from entering the water here at this time.
"We also ask that owners do not allow pets to enter the water and that people refrain from fishing.
"We will issue a further update to the public as our response to this incident continues.”