Serbia's last-ditch efforts to mend relations with Kosovo, its former province that declared independence in 2008, failed to win over European Union policy makers. Instead of starting accession talks now, the bloc Friday postponed the decision to award the country with the coveted EU candidate status to March 2012.

The bloc's verdict, which comes amid German resistance in the wake of a months-long border dispute involving Kosovo's Serbs and NATO troops that turned bloody a few days ahead of this week's EU summit, will be the...