A senior European Union official has told Kosovo that unless it approves a border demarcation deal with neighboring Montenegro it cannot enjoy EU visa liberalization.

Opposition lawmakers, who are against the deal, have disrupted parliamentary work by using tear gas canisters, blowing whistles and throwing water bottles. Street rallies by opposition supporters routinely turn into violent clashes with police.

EU Enlargement Commissioner Johannes Hahn visited Kosovo on Friday, saying that its political polarization is negatively affecting its integration path into the 28-nation bloc.

Last year Kosovo signed a stabilization and association agreement with the EU, the first step toward membership.

In 2008, Kosovo declared independence from Serbia. That is recognized by 112 countries, but not by Belgrade. Five EU members that do not recognize Kosovo have not blocked its integration steps.