Officers arrested seven suspects, all Albanians from an “important criminal organisation”, during the operation carried out in cooperation with Britain’s National Crime Agency (NCA), the Guardia Civil police force said.

Among those arrested are the two suspected ringleaders, who were detained Monday about to board a flight at Madrid airport bound for Albania, the force said in a statement.

The smugglers charged Albanians up to €15,000 to stow them away from ports in northern Spain. “The methods used to conceal them posed a risk to the life or physical integrity of the migrants, some of them minors,” the statement said.

Police said the group was believed to have been active since 2014, and would “recruit” migrants in Albania or camps near the northern ports. The smuggling network provided migrants with accommodation and food until they made their journey to Britain.

The NCA said the number of migrants the group smuggled is unknown, but around 50 people who made the crossing with their help have so far been identified by British and Spanish authorities.

“People smugglers put lives at risk, which is why disrupting and dismantling criminal networks like this is a priority,” NCA international regional manager Steve Reynolds said in a statement.

Officers seized items as part of their operation including telephones, computers, bank cards and cash receipts as well as identity documents and passports.