Polish border guards discovered over 100 kilograms of cocaine on the seabed of the Baltic Sea while conducting operations to protect critical infrastructure, authorities said Tuesday.

The drugs were found on the seabed in the area of Gdansk Bay in northern Poland. The perpetrators were subsequently identified, as were larger quantities of drugs.

Seven people were arrested in the drug case, the value of which could be as high as 60 million zlotys (14.45 million euros).

The Baltic States are on alert for any incidents involving submarine critical infrastructure. NATO has stated that it will strengthen its presence in the region after several incidents in which such infrastructure was suspiciously damaged.

Those arrested face prison sentences of up to 20 years if convicted.