Five people in Kosovo have been indicted on terrorism charges for fighting in Syria, trying to buy assault rifles and assaulting two Christian missionaries from the United States in 2013.

The indictments coincided with a vote in parliament on introducing prison sentences for waging war abroad, as the predominantly Muslim Balkan country seeks to confront the threat posed by radical Islamists returning from Syria and Iraq.

Security agencies estimate that between 100 and 200 Kosovars have enlisted with Islamic State. Most of Kosovo's 90 percent Albanian majority are Muslim but overwhelmingly secular. The bill faces one more vote in parliament before becoming law.

Following a 14-month investigation, a European Union prosecutor in Kosovo filed an indictment charging five people with "various terrorism-related offences", including the production of explosives, unlawful possession of weapons, aggravated assault and the "commission of terrorism" in Syria.

The prosecutor is part of an EU mission deployed after Kosovo's 2008 declaration of independence from Serbia, to help improve the rule of law and handle sensitive cases involving organized crime, war crimes and corruption.

In August last year, more than 40 people, including 14 imams, were arrested in Kosovo for fighting in Iraq and Syria and inspiring or recruiting people to join the fight.