Forty men suspected of fighting in Iraq and Syria have been arrested by police in Kosovo, in an operation targeting Islamist extremists.
Up to 200 Kosovo Albanians have travelled to the Middle East to fight and 16 of them have died, reports say.
Some of those held are suspected of involvement in Islamic State (IS) and Syria's Nusra Front.
Several European countries are trying to stop people volunteering for militant groups.
European Union ambassadors are expected to meet on Tuesday to consider ways of countering the group's advance in Iraq, AFP news agency reports.
Islamic State is one of the main jihadist rebel groups in Syria and is at the forefront of an insurgency against the Iraqi government.
The suspects arrested in Kosovo had either fought for or supported IS and Nusra Front, police spokesman Baki Kelani said on Monday.
"We confiscated long weapons including AK-47s, small calibre weapons, different electronic equipment, ammunition and explosives," he said.
An estimated 60 raids were carried out cross Kosovo. Among the sites targeted were makeshift mosques which may have been used as recruiting centres, he added.
President Atifete Jahjaga said in a statement that Kosovo would "not be a shelter of extremism" and the Kosovo government said any threat against the state would be punished "without mercy".
Kosovo unilaterally declared independence from Serbia in February 2008. Serbia rejects Kosovo's independence, although the two sides normalised relations in 2013.