Stockholm - A current heatwave in the Baltic Sea region has contributed to algae blooming in the sea, the Swedish Meteorological and Hydrological Institute SMHI, said Monday.

The institute and local radio reported sightings of large belts of blue-green algae, off the island of Gotland in the Baltic Sea and also in outlying parts of the Stockholm archipelago.

Experts said people should avoid swimming in waters with high concentrations of the algae, citing that it was poisonous.

Dog owners were also advised to ensure that their pets did not drink such water.

Algae blooming has been linked to the run-off of nutrients used in farming and also generated by industries and households. (dpa)