(Telecompaper) The Higher Regional Court in Duesseldorf has nullified a decision by Germany's Federal Cartel Office to approve the acquisition of cable network operator KabelBW by Liberty Global, Reuters reports. Approval of the takeover had been challenged by Deutsche Telekom. The Court ruled that the case would have to be re-examined by the anti-trust regulator. The cartel office approved the merger in December 2011 with a number of conditions, including unblocking digital channels and special rights for housing associations on the network. The deal led to the merger of Unitymedia, the second-largest German cable operator acquired the previous year by Liberty, with Kabel BW, the country's third-largest cable operator. The court found that the merger had strengthened the cable operators' dominant position and the conditions imposed by the regulator had not done enough to ensure competition. Unitymedia said that it plans to appeal to the federal court.