ATHENS, Greece, Sept. 3 (UPI) -- A type of bacteria that can present a toxic threat exists in the waters of a lake in northern Greece, scientists say.

The bacteria, which can form a dangerous algal bloom on the surface of the water, has existed in Lake Kastoria for two decades, but recent DNA tests confirmed the bacteria, called microcystis, produces toxins that could a pose a risk to public health, Kathimerini newspaper reported.

Experts from the Biology Department at Thessaloniki's Aristotle University say they could not determine whether the concentration of the bacteria in the water is currently at a potentially dangerous level.

They have urged the establishment of a group of international researchers who could examine the state of the water and suggest solutions to the problem.

One way of reducing the concentration of toxic bacteria in the water would be to introduce other "competitive" species, Maria Moustaka, a senior professor in Aristotle University's biology department, said.