Vienna (dpa) - Austria‘s low-cost airline Niki said Wednesday it would cease operations immediately after German carrier Lufthansa withdrew its takeover offer for the group.A subsidiary of now-insolvent Air Berlin, Niki had already announced a series of cancellations of flights scheduled for Thursday from its hub in Vienna. Niki has mainly served European and North African vacation destinations.Lufthansa said it was abandoning its bid to acquire the Vienna-based airline after the move was rejected by the European Commission on competition grounds.