Trading in German blue-chip index DAX and other exchanges across Europe resumed after nearly three hours of outage today due to a "technical issue" at German electronic trading platform Xetra. 

The interruption in the fully-electronic cash market trading system affected stock exchanges in Frankfurt, Vienna, Ljubljana, Prague, Budapest, Zagreb, Malta and Sofia as they use the Xetra T7 system, exchange operator Deutsche Boerse said. 

The technical snag is a further blow to Deutsche Boerse, which saw one of its longest outages in April when the Frankfurt stock exchange was halted for more than four hours. 

Its chief executive Theodor Weimer said after the April blackout that the stock exchange had taken precautions to avoid such a breakdown in the future. 

The cause of the disruption in Xetra today was not immediately clear. Deutsche Boerse spokesman Patrick Kalbhenn declined to comment. 

The German stock exchange's cash markets generated a turnover of €159.8 billio in May. 

Some European bond and stocks futures affected by the Xetra issue have also resumed trading.