Signs advising swimmers not to enter the water at Stroomi beach have been installed by North Tallinn district government and a study is being carried out to find the source of seawater pollution in the area.
The Health Board has said Stroomi beach is not a good place for swimming but bathing is not forbidden while the green flag is flying on the beach.
In recent years, water samples taken at the beach have contained bacteria found in sewage. People with poorer health and children should avoid going into the water and swallowing it.
If new water samples show the presence of bacteria in the water, the green flag will also be removed.
"We take samples every week which helps us to find out more quickly what causes the pollution," said Manuela Pihlap, deputy mayor of North Tallinn.
Editor: Helen Wright