Spanish authorities have nabbed 31 people, including 21 Bulgarians, after seizing 3 tons of cocaine brought from South America on a ship caught off the southern coast.

Most of the Bulgarian sailors arrested are from the Black Sea cities of Burgas and Varna. 6 Colombians and 4 Spaniards were also busted.

The operation was launched in January, where Spanish authorities worked in cooperation with the security forces of Bulgaria, The Maritime Executive informs.

According to Fox News, the operation was dubbed "Espartana." Branches of the drug-trafficking network in Colombia, Bulgaria and Spain were investigated as part of the operation.

An inspection of the ship, the SV Nikolay, was conducted at the Cadiz port throughout Wednesday.

The SV Nikolay ship is owned by Burgas-based company Seaborne Trade.

The company lost its connection with the ship a day before it was captured, Seaborne Trade owner Doichin Doichev has told the Bulgarian Telegraph Agency.

Doichev has promised to reveal more information on the case later on Thursday.