Police from eight European countries have busted a Balkan crime organisation allegedly running the continent’s largest cocaine distribution network.

       Authorities said on Monday that they have arrested 61 people and seized more than four metric tons of the drug.

       Police also seized 324 kilograms of marijuana, €612,000 in cash, nine luxury vehicles, and five motorbikes.

       Europol, the European Union’s police agency, said the cartel set up a "cocaine pipeline" from South America to Spain and other European countries.

       The group, which was "flooding Europe with cocaine", was pounced on after an "unprecedented international law enforcement operation," Europol said in a statement.

       The gang included violent members of paramilitary units and was “one of the most important criminal organisations operating in Europe,” Spanish police added in a press release.

       The smuggling gang was made up mostly of eastern Europeans from Serbia, Croatia, Montenegro, and Slovenia.

       Spanish intelligence services had believed that the cartel was preparing a "major cocaine importation" from South America into Europe this spring.

       The cartel was also allegedly involved in robberies, money laundering, extortion, and kidnapping, as well as the transfers of football players in Colombia, to launder their illicit drug gains. Two of the leaders of the group were known as "high-value targets" by Europol.

       The three-year police operation against the cartel began in 2018 and culminated in the arrests in March when Spanish police carried out simultaneous raids in the cities of Tarragona, Barcelona, Gerona, and Valencia.

       Thirteen individuals were arrested, including the two leaders and a police officer who had collaborated with the gang.

       The coordinated international operation involved crime-fighting agencies from Spain, Germany, Croatia, Slovenia, Serbia, and Colombia. The investigation also took police to Brazil, the Dominican Republic, and the United Arab Emirates.