Polish border guards discovered more than 100 kilograms of cocaine on the bottom of the Baltic Sea during operations to protect critical infrastructure, authorities announced on Tuesday.

The drugs were found on the seabed in the Gdańsk Bay area in northern Poland. Those involved were subsequently identified and a large quantity of drugs was seized.

Seven people have been arrested in the drug case, the value of which could reach 60 million zlotys (14,45 million euros).

The Baltic states are on high alert for any incidents involving critical underwater infrastructure. NATO has said it will strengthen its presence in the region after several incidents in which such infrastructure suffered suspected damage.

Those arrested face up to 20 years in prison if found guilty.