BELGRADE, July 19 - Serious crowd trouble marred a UEFA Cup first qualifying round match between Bosnian side Zrinjski Mostar and Serbian visitors Partizan Belgrade on Thursday.

Play was held up for 10 minutes early in the first half in Mostar after rival fans clashed with riot police and security stewards while pelting each other with flares and rocks.

Italian referee Andrea De Marco allowed the match to resume after police quelled the violence and managed to create a buffer zone between the 8,000 home fans and some 1,000 visiting supporters.

Television images showed very few police and security officials in place for what was declared a high-risk match, only the second meeting between clubs from Bosnia and Serbia since the former Yugoslavia's bloody break-up.

A hat-trick from former Zrinjski striker Lamine Diarra on his debut for Partizan helped the Serbian side to a resounding 6-1 win ahead of the return leg in Belgrade on August 2.