Police from six Western Balkan countries have arrested 22 people and seized large quantities of weapons and drugs in a coordinated operation against an international smuggling ring, Interpol said on Monday.

The Balkans region is a notorious route for smugglers of weapons and drugs to western Europe, local and European police say, and some of the guns used in last November's attacks in Paris were produced there, according to an arms manufacturer.

The police operation, code-named "Balkan Trigger", took place between April 17 and April 19 in Bosnia, Croatia, Macedonia, Montenegro, Slovenia and Serbia at the request of Interpol and was supported by Europol and Frontex, the European Union's law enforcement and border agencies, said Branislav Pavlovic, the head of Interpol's branch in Bosnia.

Police seized large quantities of guns, hand grenades, explosives, ammunition, cash, gold, vehicles and drugs, most of it in Bosnia, Pavlovic said. He did not give the nationality of those arrested or say where the arms had originated from.

Bosnia's security agencies have stepped up cooperation with their neighbours in their fight against organised crime. The director of the U.S. Central Intelligence Agency, John Brennan, visited last week to discuss anti-terrorism measures.